Why don't InfoCards work in IE8? - internet-explorer-8

What changed in IE8 that makes detecting InfoCard Selector support in javascript stop working unless IE8 is put in Compatibility Mode?
And more to the point, what is the new JavaScript code to detect the presence of InfoCard support?
Here is the script that worked up through IE7, including FireFox with a plug-in in some cases:
function AreCardsSupported() {
var IEVer = -1;
if (navigator.appName == 'Microsoft Internet Explorer') {
if (new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})").exec(navigator.userAgent) != null) {
IEVer = parseFloat(RegExp.$1);
}
}
// Look for IE 7+.
if (IEVer >= 7) {
var embed = document.createElement("object");
embed.setAttribute("type", "application/x-informationcard");
return "" + embed.issuerPolicy != "undefined" && embed.isInstalled;
}
// not IE (any version)
if (IEVer < 0 && navigator.mimeTypes && navigator.mimeTypes.length) {
// check to see if there is a mimeType handler.
x = navigator.mimeTypes['application/x-informationcard'];
if (x && x.enabledPlugin) {
return true;
}
// check for the IdentitySelector event handler is there.
if (document.addEventListener) {
var event = document.createEvent("Events");
event.initEvent("IdentitySelectorAvailable", true, true);
top.dispatchEvent(event);
if (top.IdentitySelectorAvailable == true) {
return true;
}
}
}
return false;
}

I got an answer out of band from the IE8 team:
Change
embed.setAttribute("type", "application/x-informationcard");
to
embed.type = "application/x-informationcard";

Related

How can I run useEffect on state change only and not on mount? [duplicate]

This question's answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions.
After an AJAX request, sometimes my application may return an empty object, like:
var a = {};
How can I check whether that's the case?
ECMA 5+:
// because Object.keys(new Date()).length === 0;
// we have to do some additional check
obj // 👈 null and undefined check
&& Object.keys(obj).length === 0
&& Object.getPrototypeOf(obj) === Object.prototype
Note, though, that this creates an unnecessary array (the return value of keys).
Pre-ECMA 5:
function isEmpty(obj) {
for(var prop in obj) {
if(Object.prototype.hasOwnProperty.call(obj, prop)) {
return false;
}
}
return JSON.stringify(obj) === JSON.stringify({});
}
jQuery:
jQuery.isEmptyObject({}); // true
lodash:
_.isEmpty({}); // true
Underscore:
_.isEmpty({}); // true
Hoek
Hoek.deepEqual({}, {}); // true
ExtJS
Ext.Object.isEmpty({}); // true
AngularJS (version 1)
angular.equals({}, {}); // true
Ramda
R.isEmpty({}); // true
If ECMAScript 5 support is available, you can use Object.keys():
function isEmpty(obj) {
return Object.keys(obj).length === 0;
}
For ES3 and older, there's no easy way to do this. You'll have to loop over the properties explicitly:
function isEmpty(obj) {
for(var prop in obj) {
if(obj.hasOwnProperty(prop))
return false;
}
return true;
}
For those of you who have the same problem but use jQuery, you can use jQuery.isEmptyObject.
Performance
Today 2020.01.17, I performed tests on macOS High Sierra 10.13.6 on Chrome v79.0, Safari v13.0.4, and Firefox v72.0; for the chosen solutions.
Conclusions
Solutions based on for-in (A, J, L, M) are fastest
Solutions based on JSON.stringify (B, K) are slow
Surprisingly, the solution based on Object (N) is also slow
NOTE: This table does not match the photo below.
Details
There are 15 solutions presented in the snippet below.
If you want to run a performance test on your machine, click HERE.
This link was updated 2021.07.08, but tests originally were performed here - and results in the table above came from there (but now it looks like that service no longer works).
var log = (s, f) => console.log(`${s} --> {}:${f({})} {k:2}:${f({ k: 2 })}`);
function A(obj) {
for (var i in obj) return false;
return true;
}
function B(obj) {
return JSON.stringify(obj) === "{}";
}
function C(obj) {
return Object.keys(obj).length === 0;
}
function D(obj) {
return Object.entries(obj).length === 0;
}
function E(obj) {
return Object.getOwnPropertyNames(obj).length === 0;
}
function F(obj) {
return Object.keys(obj).length === 0 && obj.constructor === Object;
}
function G(obj) {
return typeof obj === "undefined" || !Boolean(Object.keys(obj)[0]);
}
function H(obj) {
return Object.entries(obj).length === 0 && obj.constructor === Object;
}
function I(obj) {
return Object.values(obj).every((val) => typeof val === "undefined");
}
function J(obj) {
for (const key in obj) {
if (hasOwnProperty.call(obj, key)) {
return false;
}
}
return true;
}
function K(obj) {
for (var prop in obj) {
if (obj.hasOwnProperty(prop)) {
return false;
}
}
return JSON.stringify(obj) === JSON.stringify({});
}
function L(obj) {
for (var prop in obj) {
if (obj.hasOwnProperty(prop)) return false;
}
return true;
}
function M(obj) {
for (var k in obj) {
if (obj.hasOwnProperty(k)) {
return false;
}
}
return true;
}
function N(obj) {
return (
Object.getOwnPropertyNames(obj).length === 0 &&
Object.getOwnPropertySymbols(obj).length === 0 &&
Object.getPrototypeOf(obj) === Object.prototype
);
}
function O(obj) {
return !(Object.getOwnPropertyNames !== undefined
? Object.getOwnPropertyNames(obj).length !== 0
: (function () {
for (var key in obj) break;
return key !== null && key !== undefined;
})());
}
log("A", A);
log("B", B);
log("C", C);
log("D", D);
log("E", E);
log("F", F);
log("G", G);
log("H", H);
log("I", I);
log("J", J);
log("K", K);
log("L", L);
log("M", M);
log("N", N);
log("O", O);
You can use Underscore.js.
_.isEmpty({}); // true
if(Object.getOwnPropertyNames(obj).length === 0){
//is empty
}
see http://bencollier.net/2011/04/javascript-is-an-object-empty/
How about using JSON.stringify? It is almost available in all modern browsers.
function isEmptyObject(obj){
return JSON.stringify(obj) === '{}';
}
There is a simple way if you are on a newer browser.
Object.keys(obj).length === 0
Old question, but just had the issue. Including JQuery is not really a good idea if your only purpose is to check if the object is not empty. Instead, just deep into JQuery's code, and you will get the answer:
function isEmptyObject(obj) {
var name;
for (name in obj) {
if (obj.hasOwnProperty(name)) {
return false;
}
}
return true;
}
Using Object.keys(obj).length (as suggested above for ECMA 5+) is 10 times slower for empty objects! keep with the old school (for...in) option.
Tested under Node, Chrome, Firefox and IE 9, it becomes evident that for most use cases:
(for...in...) is the fastest option to use!
Object.keys(obj).length is 10 times slower for empty objects
JSON.stringify(obj).length is always the slowest (not suprising)
Object.getOwnPropertyNames(obj).length takes longer than Object.keys(obj).length can be much longer on some systems.
Bottom line performance wise, use:
function isEmpty(obj) {
for (var x in obj) { return false; }
return true;
}
or
function isEmpty(obj) {
for (var x in obj) { if (obj.hasOwnProperty(x)) return false; }
return true;
}
See detailed testing results and test code at Is object empty?
My take:
function isEmpty(obj) {
return Object.keys(obj).length === 0;
}
var a = {
a: 1,
b: 2
}
var b = {}
console.log(isEmpty(a)); // false
console.log(isEmpty(b)); // true
Just, I don't think all browsers implement Object.keys() currently.
I am using this.
function isObjectEmpty(object) {
var isEmpty = true;
for (keys in object) {
isEmpty = false;
break; // exiting since we found that the object is not empty
}
return isEmpty;
}
Eg:
var myObject = {}; // Object is empty
var isEmpty = isObjectEmpty(myObject); // will return true;
// populating the object
myObject = {"name":"John Smith","Address":"Kochi, Kerala"};
// check if the object is empty
isEmpty = isObjectEmpty(myObject); // will return false;
from here
Update
OR
you can use the jQuery implementation of isEmptyObject
function isEmptyObject(obj) {
var name;
for (name in obj) {
return false;
}
return true;
}
Just a workaround. Can your server generate some special property in case of no data?
For example:
var a = {empty:true};
Then you can easily check it in your AJAX callback code.
Another way to check it:
if (a.toSource() === "({})") // then 'a' is empty
EDIT:
If you use any JSON library (f.e. JSON.js) then you may try JSON.encode() function and test the result against empty value string.
1. Using Object.keys
Object.keys will return an Array, which contains the property names of the object. If the length of the array is 0, then we know that the object is empty.
function isEmpty(obj) {
return Object.keys(obj).length === 0 && obj.constructor === Object;
}
We can also check this using Object.values and Object.entries.
This is typically the easiest way to determine if an object is empty.
2. Looping over object properties with for…in
The for…in statement will loop through the enumerable property of object.
function isEmpty(obj) {
for(var prop in obj) {
if(obj.hasOwnProperty(prop))
return false;
}
return true;
}
In the above code, we will loop through object properties and if an object has at least one property, then it will enter the loop and return false. If the object doesn’t have any properties then it will return true.
#3. Using JSON.stringify
If we stringify the object and the result is simply an opening and closing bracket, we know the object is empty.
function isEmptyObject(obj){
return JSON.stringify(obj) === '{}';
}
4. Using jQuery
jQuery.isEmptyObject(obj);
5. Using Underscore and Lodash
_.isEmpty(obj);
Resource
function isEmpty(obj) {
for(var i in obj) { return false; }
return true;
}
The following example show how to test if a JavaScript object is empty, if by empty we means has no own properties to it.
The script works on ES6.
const isEmpty = (obj) => {
if (obj === null ||
obj === undefined ||
Array.isArray(obj) ||
typeof obj !== 'object'
) {
return true;
}
return Object.getOwnPropertyNames(obj).length === 0;
};
console.clear();
console.log('-----');
console.log(isEmpty('')); // true
console.log(isEmpty(33)); // true
console.log(isEmpty([])); // true
console.log(isEmpty({})); // true
console.log(isEmpty({ length: 0, custom_property: [] })); // false
console.log('-----');
console.log(isEmpty('Hello')); // true
console.log(isEmpty([1, 2, 3])); // true
console.log(isEmpty({ test: 1 })); // false
console.log(isEmpty({ length: 3, custom_property: [1, 2, 3] })); // false
console.log('-----');
console.log(isEmpty(new Date())); // true
console.log(isEmpty(Infinity)); // true
console.log(isEmpty(null)); // true
console.log(isEmpty(undefined)); // true
The correct answer is:
function isEmptyObject(obj) {
return (
Object.getPrototypeOf(obj) === Object.prototype &&
Object.getOwnPropertyNames(obj).length === 0 &&
Object.getOwnPropertySymbols(obj).length === 0
);
}
This checks that:
The object's prototype is exactly Object.prototype.
The object has no own properties (regardless of enumerability).
The object has no own property symbols.
In other words, the object is indistinguishable from one created with {}.
jQuery have special function isEmptyObject() for this case:
jQuery.isEmptyObject({}) // true
jQuery.isEmptyObject({ foo: "bar" }) // false
Read more on http://api.jquery.com/jQuery.isEmptyObject/
Caveat! Beware of JSON's limitiations.
javascript:
obj={ f:function(){} };
alert( "Beware!! obj is NOT empty!\n\nobj = { f:function(){} }" +
"\n\nJSON.stringify( obj )\n\nreturns\n\n" +
JSON.stringify( obj ) );
displays
Beware!! obj is NOT empty!
obj = { f:function(){} }
JSON.stringify( obj )
returns
{}
To really accept ONLY {}, the best way to do it in Javascript using Lodash is:
_.isEmpty(value) && _.isPlainObject(value)
In addition to Thevs answer:
var o = {};
alert($.toJSON(o)=='{}'); // true
var o = {a:1};
alert($.toJSON(o)=='{}'); // false
it's jquery + jquery.json
Sugar.JS provides extended objects for this purpose. The code is clean and simple:
Make an extended object:
a = Object.extended({})
Check it's size:
a.size()
Pure Vanilla Javascript, and full backward compatibility
function isObjectDefined (Obj) {
if (Obj === null || typeof Obj !== 'object' ||
Object.prototype.toString.call(Obj) === '[object Array]') {
return false
} else {
for (var prop in Obj) {
if (Obj.hasOwnProperty(prop)) {
return true
}
}
return JSON.stringify(Obj) !== JSON.stringify({})
}
}
console.log(isObjectDefined()) // false
console.log(isObjectDefined('')) // false
console.log(isObjectDefined(1)) // false
console.log(isObjectDefined('string')) // false
console.log(isObjectDefined(NaN)) // false
console.log(isObjectDefined(null)) // false
console.log(isObjectDefined({})) // false
console.log(isObjectDefined([])) // false
console.log(isObjectDefined({a: ''})) // true
IsEmpty Object, unexpectedly lost its meaning i.e.: it's programming semantics, when our famous guru from Yahoo introduced the customized non-enumerable Object properties to ECMA and they got accepted.
[ If you don't like history - feel free to skip right to the working code ]
I'm seeing lots of good answers \ solutions to this question \ problem.
However, grabbing the most recent extensions to ECMA Script is not the honest way to go. We used to hold back the Web back in the day to keep Netscape 4.x, and Netscape based pages work and projects alive, which (by the way) were extremely primitive backwards and idiosyncratic, refusing to use new W3C standards and propositions [ which were quite revolutionary for that time and coder friendly ] while now being brutal against our own legacy.
Killing Internet Explorer 11 is plain wrong! Yes, some old warriors that infiltrated Microsoft remaining dormant since the "Cold War" era, agreed to it - for all the wrong reasons. - But that doesn't make it right!
Making use, of a newly introduced method\property in your answers and handing it over as a discovery ("that was always there but we didn't notice it"), rather than a new invention (for what it really is), is somewhat 'green' and harmful. I used to make such mistakes some 20 years ago when I still couldn't tell what's already in there and treated everything I could find a reference for, as a common working solution...
Backward compatibility is important !
We just don't know it yet. That's the reason I got the need to share my 'centuries old' generic solution which remains backward and forward compatible to the unforeseen future.
There were lots of attacks on the in operator but I think the guys doing that have finally come to senses and really started to understand and appreciate a true Dynamic Type Language such as JavaScript and its beautiful nature.
My methods aim to be simple and nuclear and for reasons mentioned above, I don't call it "empty" because the meaning of that word is no longer accurate. Is Enumerable, seems to be the word with the exact meaning.
function isEnum( x ) { for( var p in x )return!0; return!1 };
Some use cases:
isEnum({1:0})
true
isEnum({})
false
isEnum(null)
false
Thanks for reading!
Best one-liner solution I could find (updated):
isEmpty = obj => !Object.values(obj).filter(e => typeof e !== 'undefined').length;
console.log(isEmpty({})) // true
console.log(isEmpty({a: undefined, b: undefined})) // true
console.log(isEmpty({a: undefined, b: void 1024, c: void 0})) // true
console.log(isEmpty({a: [undefined, undefined]})) // false
console.log(isEmpty({a: 1})) // false
console.log(isEmpty({a: ''})) // false
console.log(isEmpty({a: null, b: undefined})) // false
Another alternative is to use is.js (14kB) as opposed to jquery (32kB), lodash (50kB), or underscore (16.4kB). is.js proved to be the fastest library among aforementioned libraries that could be used to determine whether an object is empty.
http://jsperf.com/check-empty-object-using-libraries
Obviously all these libraries are not exactly the same so if you need to easily manipulate the DOM then jquery might still be a good choice or if you need more than just type checking then lodash or underscore might be good. As for is.js, here is the syntax:
var a = {};
is.empty(a); // true
is.empty({"hello": "world"}) // false
Like underscore's and lodash's _.isObject(), this is not exclusively for objects but also applies to arrays and strings.
Under the hood this library is using Object.getOwnPropertyNames which is similar to Object.keys but Object.getOwnPropertyNames is a more thorough since it will return enumerable and non-enumerable properties as described here.
is.empty = function(value) {
if(is.object(value)){
var num = Object.getOwnPropertyNames(value).length;
if(num === 0 || (num === 1 && is.array(value)) || (num === 2 && is.arguments(value))){
return true;
}
return false;
} else {
return value === '';
}
};
If you don't want to bring in a library (which is understandable) and you know that you are only checking objects (not arrays or strings) then the following function should suit your needs.
function isEmptyObject( obj ) {
return Object.getOwnPropertyNames(obj).length === 0;
}
This is only a bit faster than is.js though just because you aren't checking whether it is an object.
I know this doesn't answer 100% your question, but I have faced similar issues before and here's how I use to solve them:
I have an API that may return an empty object. Because I know what fields to expect from the API, I only check if any of the required fields are present or not.
For example:
API returns {} or {agentID: '1234' (required), address: '1234 lane' (opt),...}.
In my calling function, I'll only check
if(response.data && response.data.agentID) {
do something with my agentID
} else {
is empty response
}
This way I don't need to use those expensive methods to check if an object is empty. The object will be empty for my calling function if it doesn't have the agentID field.
We can check with vanilla js with handling null or undefined check also as follows,
function isEmptyObject(obj) {
return !!obj && Object.keys(obj).length === 0 && obj.constructor === Object;
}
//tests
isEmptyObject(new Boolean()); // false
isEmptyObject(new Array()); // false
isEmptyObject(new RegExp()); // false
isEmptyObject(new String()); // false
isEmptyObject(new Number()); // false
isEmptyObject(new Function()); // false
isEmptyObject(new Date()); // false
isEmptyObject(null); // false
isEmptyObject(undefined); // false
isEmptyObject({}); // true
I liked this one I came up with, with the help of some other answers here. Thought I'd share it.
Object.defineProperty(Object.prototype, 'isEmpty', {
get() {
for(var p in this) {
if (this.hasOwnProperty(p)) {return false}
}
return true;
}
});
let users = {};
let colors = {primary: 'red'};
let sizes = {sm: 100, md: 200, lg: 300};
console.log(
'\nusers =', users,
'\nusers.isEmpty ==> ' + users.isEmpty,
'\n\n-------------\n',
'\ncolors =', colors,
'\ncolors.isEmpty ==> ' + colors.isEmpty,
'\n\n-------------\n',
'\nsizes =', sizes,
'\nsizes.isEmpty ==> ' + sizes.isEmpty,
'\n',
''
);
It's weird that I haven't encountered a solution that compares the object's values as opposed to the existence of any entry (maybe I missed it among the many given solutions).
I would like to cover the case where an object is considered empty if all its values are undefined:
const isObjectEmpty = obj => Object.values(obj).every(val => typeof val === "undefined")
console.log(isObjectEmpty({})) // true
console.log(isObjectEmpty({ foo: undefined, bar: undefined })) // true
console.log(isObjectEmpty({ foo: false, bar: null })) // false
Example usage
Let's say, for the sake of example, you have a function (paintOnCanvas) that destructs values from its argument (x, y and size). If all of them are undefined, they are to be left out of the resulting set of options. If not they are not, all of them are included.
function paintOnCanvas ({ brush, x, y, size }) {
const baseOptions = { brush }
const areaOptions = { x, y, size }
const options = isObjectEmpty(areaOptions) ? baseOptions : { ...baseOptions, areaOptions }
// ...
}

firefox add-on sdk ToggleButton badgeColor displayed default red color

when I resized the firefox window to just not display my add-on's toggleButton, then resized the firefox window to display my add-on's toggleButton. The badgeColor was displayed with default color(red).
How should I do and solve this problem? And is this the firefox's bug?
var {ToggleButton} = require("sdk/ui/button/toggle");
var button = ToggleButton({
id:"aaaa",
label:"aaaa",
icon:{
"16":"./aaaa-16.png",
"32":"./aaaa-32.png",
"64":"./aaaa-64.png",
},
onChange:changed,
badge:"0",
badgeColor:"#A9A9A9",
});
function changed(state) {
if (button.badge == "1") {
// code
button.badge = "0";
} else {
button.badge = "1";
}
if (state.checked) {
// code
button.badgeColor = "#20B2AA";
}
else {
button.badgeColor = "#A9A9A9";
}
}

GWT 2.5 Canvas toDataURL() works in MouseUp handler but not TouchEnd Handler

I have implemented a digital signature widget using the GWT 2.5 Canvas which works great with mouse events. Unfortunately it fails miserably for touch events and I have no idea why. On a touch screen the signature is drawn but canvas.toDataURL() alway return nothing ("data:," actually). Code snippets are:
_canvas.addMouseMoveHandler(new MouseMoveHandler() {
public void onMouseMove(MouseMoveEvent event) {
int thisX = event.getRelativeX(_canvas.getElement());
int thisY = event.getRelativeY(_canvas.getElement());
if (_lastX >= 0 && _lastY >= 0) {
_exists = true;
_context.moveTo(_lastX, _lastY);
_context.lineTo(thisX, thisY);
_context.stroke();
}
_lastX = thisX;
_lastY = thisY;
}
});
_canvas.addMouseUpHandler(new MouseUpHandler() {
public void onMouseUp(MouseUpEvent event) {
_lastX = -1;
_lastY = -1;
_drawing = false;
if (_exists) _handler.sigChanged(_canvas.toDataUrl());
}
});
_canvas.addTouchMoveHandler(new TouchMoveHandler() {
public void onTouchMove(TouchMoveEvent event) {
if (event.getTouches().length() > 0) {
Touch touch = event.getTouches().get(0);
int thisX = touch.getRelativeX(_canvas.getElement());
int thisY = touch.getRelativeY(_canvas.getElement());
if (_lastX >= 0 && _lastY >= 0) {
_context.moveTo(_lastX, _lastY);
_context.lineTo(thisX, thisY);
_context.stroke();
//_handler.sigChanged(_canvas.toDataUrl());
}
_lastX = thisX;
_lastY = thisY;
}
event.preventDefault();
event.stopPropagation();
}
});
_canvas.addTouchEndHandler(new TouchEndHandler() {
public void onTouchEnd(TouchEndEvent event) {
_handler.sigChanged(_canvas.toDataUrl());
com.google.gwt.user.client.Window.alert("onTouchEnd1: " + _canvas.toDataUrl());
}
event.preventDefault();
});
Again, toDataURL() works fine for the mouse events but always return nothing in the touch events, even if you call it from the touch move handler. Any help or suggestions would be greatly appreciated.
I borrowed a friends android phone that is running a newer version (4.1 vs 2.3) and it works. I don't understand it but I assume it's a bug with GWT 2.5 and I'm moving on.
James

XNA Hold screen to move object

im working with windows phone game using xna... and looking a way to make my object to move with holding some rectangle that i made as a button on screen....
i already tried this but it just read tap gesture only
foreach (GestureSample gestureSample in input.Gestures)
{
switch (gestureSample.GestureType)
{
case GestureType.Hold:
case GestureType.Tap:
Point tapLocation = new Point((int)gestureSample.Position.X, (int)gestureSample.Position.Y);
if (rightRectangle.Contains(tapLocation))
{
rightTouched = true;
player.Catapult.CurrentState = CatapultState.MoveRight;
playerPositionUpdate.X += 20;
player.catapultPosition.X += 20;
player.Catapult.catapultPosition.X += 20;
player.Catapult.projectilePositionUpdate.X += 20;
if (player.Catapult.catapultPosition.X == player.Catapult.catapultPosition.X + 20)
rightTouched = false;
CenterOnPosition(player.Catapult.Position - catapultCenterOffset);
}
break;
}
}
Gestures are discrete events. You want to poll the state of the touch panel every frame. Use TouchPanel.GetState() for that.
See Working with Touch Input (Windows Phone) for information.
As mentioned above you shouldn't use GestureSample for that purpose, because using dragcomplete and freedrag a bit tricky. Instead you should code your own gestures using TouchPanel.GetState()
TouchCollection touchCollection = TouchPanel.GetState();
if (touchCollection.Count == 1)
{
var touch = touchCollection[0];
switch (touch.State)
{
case TouchLocationState.Pressed:
if (rectangle.Contains((int) touch.Position.X, (int) touch.Position.Y))
{
isMoving = true;
}
break;
case TouchLocationState.Moved:
if (isMoving)
{
TouchLocation prevLocation;
touch.TryGetPreviousLocation(out prevLocation);
if (prevLocation.Position != touch.Position)
{
Vector2 delta = touch.Position - prevLocation.Position;
//offset your rectangle on delta
}
}
break;
case TouchLocationState.Released:
isMoving = false;
break;
}
}
else if (touchCollection.Count == 2)
{
var touchOne = touchCollection[0];
var touchTwo = touchCollection[1];
//pinch logic here
}
I guess you understand the idea.

Tracking with Java Script if Ajax request is going on in a webpage or Intercept XMLHttpRequest through Selenium Web driver

I am using Selenium WebDriver for crawling a web site(only for example, I will be crawling other web sites too!) which has infinite scroll.
Problem statement:
Scroll down the infinite scroll page till the content stops loading using Selenium web driver.
My Approach:
Currently I am doing this-
Step 1: Scroll to the page bottom
JavascriptExecutor js = (JavascriptExecutor) driver;
js.executeScript("javascript:window.onload=toBottom();"+
"function toBottom(){" +
"window.scrollTo(0,Math.max(document.documentElement.scrollHeight," +
"document.body.scrollHeight,document.documentElement.clientHeight));" +
"}");
Then I wait for some time to let the Ajax Request complete like this-
Step 2: Explicitly wait for Ajax request to be over
Thread.sleep(1000);
Then I give another java script to check if the page is scrollable
Step 3:Check if the page is scrollable
//Alternative to document.height is to be used which is document.body.clientHeight
//refer to https://developer.mozilla.org/en-US/docs/DOM/document.height
if((Long)js.executeScript("return " +
"(document.body.clientHeight-(window.pageYOffset + window.innerHeight))")>0)
If the above condition is true then I repeat the from Step 1 - 3, till condition in Step 3 is false.
The Problem:
I do not want to give the Thread.sleep(1000); in step 2, rather I would like to check using Java Script if the background Ajax request is over and then scroll down further if the condition in Step 3 is true .
PS: I am not the developer of the page so I do not have access to the code running the page, I can just inject java scripts(as in Step 1 and 3) in the web page. And, I have to write a generic logic for any web site with Ajax requests during infinite scroll.
I will be grateful to some one could spare some time here!
EDIT : Ok, after struggling for 2 days, I have figured out that the pages which I am crawling through the Selenium WebDriver can have any of these JavaScript libraries and I will have to pool according to the different Library, for example, In case of the web application using jQuery api, I may be waiting for
(Long)((JavascriptExecutor)driver).executeScript("return jQuery.active")
to return a zero.
Likewise if the web application is using the Prototype JavaScript library I will have to wait for
(Long)((JavascriptExecutor)driver).executeScript("return Ajax.activeRequestCount")
to return a zero.
Now, the problem is how do I write a generic code which could handle most the JavaScript libraries available?
Problem I am facing in implementing this-
1. How do I find which JavaScript Library is being used in the Web Application(using Selenium WebDriver in Java), such that I can then write the corresponding wait methods?
Currently, I am using this
Code
2. This way I will have to write as many as 77 methods for separate JavaScript library so, I need a better way to handle this scenario as well.
In short, I need to figure out if the browser is making any call(Ajax or simple) with or without any JavaScript library through Selenium Web Driver's java implementation
PS: there are Add ons for Chorme's JavaScript Lib detector and Firefox's JavaScript Library detector which detect the JavaScript library being used.
For web pages with Ajax Response during the infinite scroll and using jQuery API(or other actions), before starting to opening the web page.
//Inject the pooling status variable
js.executeScript("window.status = 'fail';");
//Attach the Ajax call back method
js.executeScript( "$(document).ajaxComplete(function() {" +
"status = 'success';});");
Step 1: will remain the same as in the original question
Step 2 Pooling the following script(This is the one which removes the need of Thread.Sleep() and makes the logic more dynamic)
String aStatus = (String)js.executeScript("return status;");
if(aStatus!=null && aStatus.equalsIgnoreCase("success")){
js.executeScript("status = 'fail';");
break poolingLoop;
}
Step 3: No need now!
Conclusion: No need to give blunt Thread.sleep(); again and again while using Selenium WebDriver!!
This approach works good only if there's jQuery api being used in the web application.
EDIT:
As per the the link given by #jayati i injected the javascript-
Javascript one:
//XMLHttpRequest instrumentation/wrapping
var startTracing = function (onnew) {
var OldXHR = window.XMLHttpRequest;
// create a wrapper object that has the same interfaces as a regular XMLHttpRequest object
// see http://www.xulplanet.com/references/objref/XMLHttpRequest.html for reference on XHR object
var NewXHR = function() {
var self = this;
var actualXHR = new OldXHR();
// private callbacks (for UI):
// onopen, onsend, onsetrequestheader, onupdate, ...
this.requestHeaders = "";
this.requestBody = "";
// emulate methods from regular XMLHttpRequest object
this.open = function(a, b, c, d, e) {
self.openMethod = a.toUpperCase();
self.openURL = b;
ajaxRequestStarted = 'open';
if (self.onopen != null && typeof(self.onopen) == "function") {
self.onopen(a,b,c,d,e); }
return actualXHR.open(a,b,c,d,e);
}
this.send = function(a) {
ajaxRequestStarted = 'send';
if (self.onsend != null && typeof(this.onsend) == "function") {
self.onsend(a); }
self.requestBody += a;
return actualXHR.send(a);
}
this.setRequestHeader = function(a, b) {
if (self.onsetrequestheader != null && typeof(self.onsetrequestheader) == "function") { self.onsetrequestheader(a, b); }
self.requestHeaders += a + ":" + b + "\r\n";
return actualXHR.setRequestHeader(a, b);
}
this.getRequestHeader = function() {
return actualXHR.getRequestHeader();
}
this.getResponseHeader = function(a) { return actualXHR.getResponseHeader(a); }
this.getAllResponseHeaders = function() { return actualXHR.getAllResponseHeaders(); }
this.abort = function() { return actualXHR.abort(); }
this.addEventListener = function(a, b, c) { return actualXHR.addEventListener(a, b, c); }
this.dispatchEvent = function(e) { return actualXHR.dispatchEvent(e); }
this.openRequest = function(a, b, c, d, e) { return actualXHR.openRequest(a, b, c, d, e); }
this.overrideMimeType = function(e) { return actualXHR.overrideMimeType(e); }
this.removeEventListener = function(a, b, c) { return actualXHR.removeEventListener(a, b, c); }
// copy the values from actualXHR back onto self
function copyState() {
// copy properties back from the actual XHR to the wrapper
try {
self.readyState = actualXHR.readyState;
} catch (e) {}
try {
self.status = actualXHR.status;
} catch (e) {}
try {
self.responseText = actualXHR.responseText;
} catch (e) {}
try {
self.statusText = actualXHR.statusText;
} catch (e) {}
try {
self.responseXML = actualXHR.responseXML;
} catch (e) {}
}
// emulate callbacks from regular XMLHttpRequest object
actualXHR.onreadystatechange = function() {
copyState();
try {
if (self.onupdate != null && typeof(self.onupdate) == "function") { self.onupdate(); }
} catch (e) {}
// onreadystatechange callback
if (self.onreadystatechange != null && typeof(self.onreadystatechange) == "function") { return self.onreadystatechange(); }
}
actualXHR.onerror = function(e) {
ajaxRequestComplete = 'err';
copyState();
try {
if (self.onupdate != null && typeof(self.onupdate) == "function") { self.onupdate(); }
} catch (e) {}
if (self.onerror != null && typeof(self.onerror) == "function") {
return self.onerror(e);
} else if (self.onreadystatechange != null && typeof(self.onreadystatechange) == "function") {
return self.onreadystatechange();
}
}
actualXHR.onload = function(e) {
ajaxRequestComplete = 'loaded';
copyState();
try {
if (self.onupdate != null && typeof(self.onupdate) == "function") { self.onupdate(); }
} catch (e) {}
if (self.onload != null && typeof(self.onload) == "function") {
return self.onload(e);
} else if (self.onreadystatechange != null && typeof(self.onreadystatechange) == "function") {
return self.onreadystatechange();
}
}
actualXHR.onprogress = function(e) {
copyState();
try {
if (self.onupdate != null && typeof(self.onupdate) == "function") { self.onupdate(); }
} catch (e) {}
if (self.onprogress != null && typeof(self.onprogress) == "function") {
return self.onprogress(e);
} else if (self.onreadystatechange != null && typeof(self.onreadystatechange) == "function") {
return self.onreadystatechange();
}
}
if (onnew && typeof(onnew) == "function") { onnew(this); }
}
window.XMLHttpRequest = NewXHR;
}
window.ajaxRequestComplete = 'no';//Make as a global javascript variable
window.ajaxRequestStarted = 'no';
startTracing();
Or Javascript Two:
var startTracing = function (onnew) {
window.ajaxRequestComplete = 'no';//Make as a global javascript variable
window.ajaxRequestStarted = 'no';
XMLHttpRequest.prototype.uniqueID = function() {
if (!this.uniqueIDMemo) {
this.uniqueIDMemo = Math.floor(Math.random() * 1000);
}
return this.uniqueIDMemo;
}
XMLHttpRequest.prototype.oldOpen = XMLHttpRequest.prototype.open;
var newOpen = function(method, url, async, user, password) {
ajaxRequestStarted = 'open';
/*alert(ajaxRequestStarted);*/
this.oldOpen(method, url, async, user, password);
}
XMLHttpRequest.prototype.open = newOpen;
XMLHttpRequest.prototype.oldSend = XMLHttpRequest.prototype.send;
var newSend = function(a) {
var xhr = this;
var onload = function() {
ajaxRequestComplete = 'loaded';
/*alert(ajaxRequestComplete);*/
};
var onerror = function( ) {
ajaxRequestComplete = 'Err';
/*alert(ajaxRequestComplete);*/
};
xhr.addEventListener("load", onload, false);
xhr.addEventListener("error", onerror, false);
xhr.oldSend(a);
}
XMLHttpRequest.prototype.send = newSend;
}
startTracing();
And checking the status of the status vars ajaxRequestStarted, ajaxRequestComplete in the java code, one can determine if the ajax was started or completed.
Now I have a way to wait till an Ajax is complete, I can also find if the Ajax was triggered on some action
Approach 1:
Your approach is good, just a few changes would do the trick:
Step 1: Improve this step to call the toBottom function at regular interval using window.setInterval. At (c >= totalcount) call window.clearInterval
Setp 2: Instead of checking the page is yet scrollable, check if (c >= totalcount). And this condition every 200ms until (c >= totalcount) returns true.
FYI: If the Step 1 doesn't work in all the browsers then probably, you can refer to line 5210 of Tata-Nano-Reviews-925076578.js and call this with cvariable checking.
Approach 2:
Go to jQuery API and type "ajax". You can find some callback handlers which could be used for ajax requests.
Probably, set a variable before the request is been sent and after it is been received appropriately.
And in between use your original method of scrolling to bottom at regular interval, unless you can no more scroll. At this point clear the interval variable.
Now, regularly check if that interval variable is null or not. Null would mean that you have reached the bottom.
We had to solve the same problem, and managed using a long Javascript function. Just need to add checks to see which library is not undefined.
PS Thanks for giving me an easy answer for how to check for in progress Prototype requests!
eg. Handle JQuery and XHR/Prototype
var jsExecutor = /*Get your WebDriverInstance*/ as IJavaScriptExecutor;
while(/*your required timeout here*/)
{
var ajaxComplete =
jsExecutor.ExecuteScript("return ((typeof Ajax === 'undefined') ||
Ajax.activeRequestCount == 0) && ((typeof jQuery === 'undefined') || $.active == 0)");
if (ajaxIsComplete)
return
}

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