Validating file extensions from an array

Question

I have searched the Web and SO to figure this one out by myself with many different ways, but with no success.

I would like to show a message if the file extension is accepted or not, in the same fashion as the "outpush.push" statements.

This would need to be taken from an ARRAY of accepted file extensions such as JPG, PNG, GIF and detect if the file extension is uppercase and accept it (convert it to lowercase).

Here is my script. Am wondering how and where in the script could I implement such a feature?

function handleFileSelect(evt) {

    var files = evt.target.files; // FileList object
    var max_size = 5120; // Max file size

    var output = [];
    for (var i = 0, f; f = files[i]; i++) {

        output.push('<li><strong><font size="3" color="FFFFFF">FILE: ', escape(f.name), '</strong> (', f.type || 'n/a', ') - ',
            f.size, ' bytes, last modified: ',
            f.lastModifiedDate ? f.lastModifiedDate.toLocaleDateString() : 'n/a',
            '</font></li>');

        if(f.size > max_size) {

            output.push('<font size="5" color="FFFF00"><b>ERROR!! Sorry, but the file that you selected is too large. Please upload a file that is no larger than ' + max_size + ' KB.');
        }

        if(f.size < max_size) {
            output.push('<font size="5" color="FFFF00"><b>FILE SIZE OK. CLICK TO SEND button below.</font>');

            output.push('<font size="5" color="FFFFFF"><hr><b>IMPORTANT: Do not close this window. Wait till you see the next page when finished uploading your file.</font>');

            document.getElementById("myButton").style.display="all";
        }

    }

    document.getElementById('list').innerHTML = '<ul>' + output.join('') + '</ul>';
}

document.getElementById('files').addEventListener('change', handleFileSelect, false);

Where is the jQuery? All of this looks like basic JavaScript. — Jeff B
– Jeff B, Commented Mar 1, 2013 at 19:18
There are already answers below, but I will add that you have if(f.size > max_size) and if(f.size < max_size). The second should just be an else statement. Also, if f.size == max_size, you won't get any message. — Jeff B
– Jeff B, Commented Mar 1, 2013 at 19:37
@JeffB - I got rid of one statement and replaced with the other, and still no success. I can't pinpoint where it's failing. — Funk Forty Niner
– Funk Forty Niner, Commented Mar 1, 2013 at 20:13

Jeff B · Accepted Answer · 2013-03-01 22:00:13Z

There are a couple of issues with your code.

1) You should use an if-else, instead of multiple if statements:

if (f.size > max_size) {
    // ...
} else {
    // ...
}

2) all is not a valid value for display, use block or inline:

document.getElementById("myButton").style.display = "block";

3) You are using outdated <font> tags. Instead, use styles and CSS. In your case, I would use classes, one for a msg, plus additional classes for error, important, and ok.

4) To do the array check, just use indexOf():

var extensions = ["jpg", "jpeg", "txt", "png"];  // Globally defined

...

// Get extension and make it lowercase
// This uses a regex replace to remove everything up to 
// and including the last dot
var extension = f.name.replace(/.*\./, '').toLowerCase();

if (extensions.indexOf(extension) < 0) {  // Wasn't found
    output.push('<li class="msg error">ERROR!! Sorry, but the file that you selected is not a valid file type.  Valid types are: ', valid, '</li>');
} else ...

Demo: http://jsfiddle.net/jtbowden/L2Gps/

RenegadeMatrix · Accepted Answer · 2013-03-01 19:23:15Z

2

You can have the array as something like this:

var file_types = {'jpg', 'png', 'gif'};

and then do something like this in your for-loop

if ($.inArray(f.ext, file_types) == -1) {
output.push('<font size="5" color="FFFF00"><b>ERROR!! Incorrect file type! Accepted file types are : jpg, png, gif</b></font>');
}

1 Comment

RenegadeMatrix Over a year ago

The other answers are good for vanilla javascript. I'll keep this answer up for reference

Andy Jones · Accepted Answer · 2013-03-01 19:28:42Z

0

You can try one of two approaches - either try a grab the extension and match it against an array of allowed extensions, or a regular expression.

var accepted_types = ['jpg', 'gif', 'png'];
if (accepted_types.indexOf(f.ext) > 0) {
  output.push(...);
}

As for the jQuery - you might consider the following for building your HTML

var file_list = $("<ul></ul>");
for (var i = 0, f; f = files[i]; i++) {
  // work goes here, simply append the list elements into file_list
  file_list.append($("<li>" ... "</li>"));
}

// to append your new list to id="list"
$("#list").append(file_list);
// or to replace the html with your new html
$("#list").html(file_list.html());

answered Mar 1, 2013 at 19:28

Andy Jones

6,2804 gold badges33 silver badges47 bronze badges

Collectives™ on Stack Overflow

Validating file extensions from an array

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related