I'm trying to validate file extensions in javascript. When I use just one argument in my if statement like this
if(ext!='png' ){ bodyAppend("err","Incorrect file type"); bodyAppend("br",""); } the code works. But if I add an or statement like this
if(ext!='png' || ext!='jpg'){ bodyAppend("err","Incorrect file type"); bodyAppend("br",""); } the code does not work and always returns true.
You need to use &&, not ||
The problem with the logic:
ext!='png' || ext!='jpg' is that as soon as the extension is one of those options ("png" or "jpg"), it's NOT the other, so the opposite comparison will always be true. If it's "png", it's NOT "jpg". If it's "jpg", it's NOT "png".
I have this problem a lot with SQL queries. When you're writing out a condition with many comparisons, just try saying it out loud. If the extension is NOT "png" and the extension is NOT "jpg", then throw an error.
@anpgall's answer is correct, but if you end up with a large number of extensions to check, this code might be easier to maintain.
// At the top of your function var imageExts = ['png', 'jpg', 'gif']; // later // Perhaps setting ext to lower case. if (imageExts.indexOf(ext) === -1) { bodyAppend("err","Incorrect file type"); } If you need to target older versions of IE, you can include this polyfill
https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/indexOf
My guess is you need && (and), not || (or).
With &&, it is false only if the extension is not equal to both of them.
With ||, it is true if for instance ext === 'png' because the other condition will return true (and hence the entire condition be true) because it is !== to 'jpg'.
I would suggest this way of validating the file extension in JavaScript using jQuery:
HTML
<input id="file" type="file" class="findDocumentGeneral"> Javascript/Jquery
var extension = $('.findDocumentGeneral').val().split('.').pop().toLowerCase(); if (~$.inArray(extension, ['jpg', 'jpeg', 'gif', 'png', 'pdf', 'docx'])) { alert(extension); // to see if it works correctly } else { alert("Incorrect file type."); } It's readable and works perfectly.
