how to restrict double extension while uploading file to server - nodejs-server

Question

fileName = inputParam.file_name.split('.')[0].toLowerCase().replace(/ /g, '') + '' + Date.now() + "." + (fileData.file.name.split('.')[1] || inputParam.file_name.split('.')[1])
filePath = filePath + fileName
This is the condition I am using.
For example it should only restrict a.jpeg.jpg or a.php.jpeg. and allow extension like a.a.jpeg or bird.tree.jpeg

Answer 1

var _validFilejpeg = [".jpeg", ".jpg", ".bmp", ".png",".pdf", ".txt"];
var invalid = [".php",".php5", ".pht", ".phtml", ".shtml", ".asa", ".cer", ".asax", ".swf",".xap"];
function validateForSize(oInput, minSize, maxSizejpeg) {
//if there is a need of specifying any other type, just add that particular type in var _validFilejpeg
if (oInput.type == "file") {
var sFileName = oInput.value;
var file = sFileName.match(/\d/g);
var fileExt = sFileName.substr(sFileName.length-4);
if (sFileName.length > 0) {
var blnValid = false;
for (var j = 0; j < _validFilejpeg.length; j++) {
var sCurExtension = _validFilejpeg[j];
if (sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length)
.toLowerCase() == sCurExtension.toLowerCase()) {
blnValid = true;
break;
}
}
if(fileExt = 'invalid'){
alert("Your document does not have a proper file extension.")
blnValid = false;
}
if(fileExt = 'file'){
alert("Your document does not have a proper file extension.")
blnValid = false;
}
if (!blnValid) {
alert("Sorry, this file is invalid, allowed extension is: " + _validFilejpeg.join(", "));
oInput.value = "";
return false;
}
}
}
fileSizeValidatejpeg(oInput, minSize, maxSizejpeg);
}
function fileSizeValidatejpeg(fdata, minSize, maxSizejpeg) {
if (fdata.files && fdata.files[0]) {
var fsize = fdata.files[0].size /1024; //The files property of an input element returns a FileList. fdata is an input element,fdata.files[0] returns a File object at the index 0.
//alert(fsize)
if (fsize > maxSizejpeg || fsize < minSize) {
alert('This file size is: ' + fsize.toFixed(2) +
"KB. Files should be in " + (minSize) + " to " + (maxSizejpeg) + " KB ");
fdata.value = ""; //so that the file name is not displayed on the side of the choose file button
return false;
} else {
console.log("");
}
}
}
<input type="file" onchange="validateForSize(this,20,5000);" >

Answer 2

You can simply do this
if (fileName.split('.').length > 2) {
throw new Error('Double extension file detected')
}