Jquery Mobile + Phonegap improve listview performance - performance

Question

In my JQM 1.4 + Phonegap 3.6 app, I am using a listview as in the following code.
HTML:
<div id="boardselection">
<ul id="modelsListview" data-role="listview" data-icon="false">
</ul>
</div>
JS:
function resetModelsListView(prodata, firsttime, funfeatureOn, specificBrand, specificPro) {
console.log("on passe dans resetModelsListView");
// funfeatureOn = 0;
//debug timer
var time = [];
var dummy;
var i;
var listviewdeferred = $.Deferred();
var optionspro = '';
var optionsbrand = '';
var optionsmodel = '';
var countpros = 0;
var countbrands = 0;
var countmodels = 0;
var chosenmodelListViewHandle = $('#modelsListview');
var chosenbrandSelect = $('#chosenbrand');
optionsmodel += '';
var alreadyusedbrands = [];
prodata.sort(SortByName);
// get previously selected model to reselect it later
//var previouslySelectedModelId =parseInt(chosenmodelSelect.find('li:selected').val());
if (!funfeatureOn) {
prodata.sort(SortByModel);
} else {
prodata.sort(SortByFUN);
}
//populate model list
//~ if (firsttime){
//~ var perfIsChecked = true;
//~ var smallwaveIsChecked = true;
//~ var stepupIsChecked = true;
//~ }else {
var perfIsChecked = $('#checkboxperf').is(":checked");
var smallwaveIsChecked = $('#checkboxsmallwave').is(":checked");
var stepupIsChecked = $('#checkboxstepup').is(":checked");
//~ }
console.log("perfIsChecked, smallwaveIsChecked, stepupIsChecked =");
console.log(perfIsChecked);
console.log(smallwaveIsChecked);
console.log(stepupIsChecked);
//if none checked then no filter
if (!perfIsChecked && !smallwaveIsChecked && !stepupIsChecked) {
perfIsChecked = true;
smallwaveIsChecked = true;
stepupIsChecked = true;
}
for (i = 1; i < prodata.length; ++i) {
if (specificBrand && prodata[i]['brand'] != specificBrand) {
} else if (specificPro && prodata[i]['name'] != specificPro) {
} else {
if (prodata[i]['fun'] == 0 && perfIsChecked) {
optionsmodel += '<li><a class="optionfuninit" href="#" data-proid="' + prodata[i]['id'] + '"><div class="listviewtexts"><span class="listviewtextsmodel">' + prodata[i]['model'] + '</span> - <span class="listviewtextspro">as surfed by ' + prodata[i]['name'] + '</span></div></a></li>';
} else if (prodata[i]['fun'] == 1 && smallwaveIsChecked) {
optionsmodel += '<li><a class="optionfuninit" href="#" data-proid="' + prodata[i]['id'] + '"><div class="listviewtexts"><span class="listviewtextsmodel">' + prodata[i]['model'] + '</span> - <span class="listviewtextspro">as surfed by ' + prodata[i]['name'] + '</span></div></a></li>';
} else if (prodata[i]['fun'] == 2 && stepupIsChecked) {
optionsmodel += '<li><a class="optionstepupinit" href="#" data-proid="' + prodata[i]['id'] + '"><div class="listviewtexts"><span class="listviewtextsmodel">' + prodata[i]['model'] + '</span> - <span class="listviewtextspro">as surfed by ' + prodata[i]['name'] + '</span></div></a></li>';
} else if (prodata[i]['fun'] == 3 && smallwaveIsChecked) {
optionsmodel += '<li><a class="optionkidsinit" href="#" data-proid="' + prodata[i]['id'] + '"><div class="listviewtexts"><span class="listviewtextsmodel">' + prodata[i]['model'] + '</span> - <span class="listviewtextspro">as surfed by ' + prodata[i]['name'] + '</span></div></a></li>';
}
if (prodata[i]['model'] !== prodata[i - 1]['model']) { //eliminate name duplicates if prodata sorted by model
countmodels = countmodels + 1;
}
}
}
chosenmodelListViewHandle.html(optionsmodel);
if (chosenmodelListViewHandle.listview("option", "disabled")) {
chosenmodelListViewHandle.listview("option", "disabled", false);
}
//~ if (resetModelsOnly) {
//~ if ( !isNaN(previouslySelectedModelId) ) {
//~ chosenmodelListViewHandle.find('li[href="' + previouslySelectedModelId + '"]').attr("selected", "selected").siblings('li').removeAttr('selected');
//~ }
//~ }
//~ highlightFunModels(funfeatureOn, 1);
//~ highlightStepupModels(funfeatureOn, 0);
chosenmodelListViewHandle.listview("refresh", true);
$("#chosenmodel-button").addClass("ui-icon-carat-d ui-btn-icon-right");
if (!funfeatureOn) {
} else {
$('ul#chosenmodel-menu').find("a.ui-btn:contains(SMALL-WAVE)").addClass("optionfun");
$('ul#chosenmodel-menu').find("a.ui-btn:contains(STEP-UP)").addClass("optionstepup");
}
prodata.sort(SortById); //we need this otherwise prodata is not usable by the $('#chosenpro').trigger
$("#chosenmodel-button span").attr({ 'data-i18n': 'select.3' });
$("#boardselection").i18n();
listviewdeferred.resolve();
return listviewdeferred;
}
This dynamically displays a long list of images and text, depending on wether filters (checkboxes) are checked or not, and this list is quite long to generate and particularly difficult to scroll in iOS.... The performance is bad.
Can you help me figure out a way to improve the performance.

Answer 1

The accepted answer is not correct. Your code is slow, but not because of jQuery Mobile. Take a look at the loop in your jsFiddle: jsfiddle.net/L3gr46s8/4
for (i = 0; i <= 50; i++) {
$('ul[data-role="listview"]').append('<li>' + 'list item ' + i + '</li>');
$('ul[data-role="listview"]').listview('refresh');
}
There are a couple very significant problems in those four lines of code.
First, your code executes two DOM traversals to locate the ul on the page. You could execute $('ul[data-role="listview"]') before the loop and store the result in a variable:
var listView = $('ul[data-role="listview"]');
Second, your code inserts the list item directly to the DOM and you instruct jQuery Mobile to immediately apply markup enhancement with .listview('refresh');. This is extraordinarily expensive! Especially on under-powered mobile devices. Depending upon the browser and page layout, those two lines could trigger a full page re-draw with every iteration of the loop.
You should render the content as a DocumentFragment (in memory), insert it all to the DOM in one action and tell JQM to enhance the markup once at the end. Even simply moving $('ul[data-role="listview"]').listview('refresh'); out of the loop would be a dramatic improvement.
Here is some additional reading on the importance of rendering your content first in memory before inserting it into the DOM:
How expensive is it to dynamically insert DIVs using JavaScript?
John Resig - DOM DocumentFragments

Answer 2

To put it short, jQuery Mobile is simply slow.
I have a dynamic listview in my app and also had performance issues when using jQuery Mobile. I came to a conclusion that the issue was in rendering and was caused by jQuery Mobile. I implemented my own styling and the rendering time came down from 170ms to 25ms.
Here's some backup to my point (3 articles): http://apachecordova.blogspot.fi/search/label/jQuery%20Mobile
EDIT:
As an answer to your question in the comments, I don't think it would help if I posted my code here. The whole point is that you only write the code YOU need. My listview probably is totally different than yours.
To prove my point (again), I made two listviews. The first one is a basic jQM listview. The other one is styled with custom CSS and it's pretty close to what I use in my app. There's a button in both which renders the listview. What is happening under the hood is very different:
jQM: As you can see, there's a lot of stuff (that you may not need) going on
Custom CSS: attached an event listener to all the elements to make the comparison more fair
These profiles have been recorded with Chrome Developer Tools and the difference is obvious: 173ms vs 12ms. This custom CSS took me about 5min to write:
#custom-listview {
list-style-type: none;
padding: 0px;
margin: 0px;
}
#custom-listview li {
display: block;
position: relative;
overflow: visible;
}
#custom-listview a {
display: block;
position: relative;
text-overflow: ellipsis;
text-decoration: none;
color: white;
padding: .7em 1em;
font-size: 16px;
background-color: #333;
border: solid 1px #1f1f1f;
overflow: hidden;
white-space: nowrap;
font-family: sans-serif;
}
I had to add some code here, because SO won't let me link to Fiddle without:
jQM
Custom CSS
I'm not saying jQuery Mobile is all bad. It's good for many things. But if you have complex structure and/or a lot of data, the performance may become an issue especially in PhoneGap apps. That's the conclusion I have come to with my little experience.