jquery - Check for file extension before uploading

You can achieve this using JQuery

HTML

 <input type="file" id="FilUploader" />

JQuery

    $("#FilUploader").change(function () {
        var fileExtension = ['jpeg', 'jpg', 'png', 'gif', 'bmp'];
        if ($.inArray($(this).val().split('.').pop().toLowerCase(), fileExtension) == -1) {
            alert("Only formats are allowed : "+fileExtension.join(', '));
        }
    });

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If you want to do it without a plugin you could use the following.

Javascript, using jQuery:

$(document).ready( function (){
    $("#your_form").submit( function(submitEvent) {

        // get the file name, possibly with path (depends on browser)
        var filename = $("#file_input").val();

        // Use a regular expression to trim everything before final dot
        var extension = filename.replace(/^.*\./, '');

        // Iff there is no dot anywhere in filename, we would have extension == filename,
        // so we account for this possibility now
        if (extension == filename) {
            extension = '';
        } else {
            // if there is an extension, we convert to lower case
            // (N.B. this conversion will not effect the value of the extension
            // on the file upload.)
            extension = extension.toLowerCase();
        }

        switch (extension) {
            case 'jpg':
            case 'jpeg':
            case 'png':
                alert("it's got an extension which suggests it's a PNG or JPG image (but N.B. that's only its name, so let's be sure that we, say, check the mime-type server-side!)");

            // uncomment the next line to allow the form to submitted in this case:
//          break;

            default:
                // Cancel the form submission
                submitEvent.preventDefault();
        }

  });
});

HTML:

<form id="your_form" method="post" enctype="multipart/form-data">
    <input id="file_input" type="file" />
    <input type="submit">
</form>

I would like to thank the person who posted the answer, but he has deleted the post. We can do it like this.

$("#yourElem").uploadify({
   'uploader': ...,
   'script': ...
    'fileExt' : '*.jpg;*.gif;', //add allowed extensions
    .....,
    'onSelect': function(e, q, f) {
        var validExtensions = ['jpg','gif']; //array of valid extensions
        var fileName = f.name;
        var fileNameExt = fileName.substr(fileName.lastIndexOf('.') + 1);
        if ($.inArray(fileNameExt, validExtensions) == -1){
           alert("Invalid file type");
           $("#yourElem").uploadifyCancel(q);
           return false;
        }
    }
});

Thanks for the answer, it really worked...

Here is a simple code for javascript validation, and after it validates it will clean the input file.

<input type="file" id="image" accept="image/*" onChange="validate(this.value)"/>

function validate(file) {
    var ext = file.split(".");
    ext = ext[ext.length-1].toLowerCase();      
    var arrayExtensions = ["jpg" , "jpeg", "png", "bmp", "gif"];

    if (arrayExtensions.lastIndexOf(ext) == -1) {
        alert("Wrong extension type.");
        $("#image").val("");
    }
}