Check if a file exists with JQuery on local server (in a loop)

Question

First of all, I already found this solution here: How do I check if file exists in jQuery or JavaScript?

I also tried to use that snippet, but it ends in an infinite-loop for some reason and the response is always "undefined" (even without the loop).

Update

It seems that a redirect-problem of the CMS in the same webspace is causing the infiniteloop. If I'm reading this right, the script stops where it should, but starts running over and over again.

For some reason, the statusCode-effect isn't triggering as well. The log with "nope" never occurs. In Firebug, at the file which isn't existing, it throws a 303 headercode.

HEAD mySite/papger6/index.png

303 See Other 86ms

(Changing the statusCode from 404 to 303 didn't solve the problem.

Update 2

After deleting the CMS and leaving only this script alone, it still runs infinite without triggering the "false" or "failure"-part.

My code now looks like this:

function lookForFiles(helper, imageArray) {

    var base_url = window.location.origin;
    var pathArray = window.location.pathname.split( '/' );

    var absUrl = base_url+"/"+pathArray[1];

    $.ajax({
        url: absUrl + '/paper' + helper + '/index.png',
        type: 'HEAD',
        statusCode: {
            404: function () {
                console.log('nope');
                return imageArray;
            }
        },
        success: function () {
            console.log(absUrl + '/paper' + helper + '/index.png');
            imageArray[helper - 1] = 'paper' + helper + '/index.png';
            helper++;
            lookForFiles(helper, imageArray);
        }
    });
}

I have a folderstructure like this:

root
 -> paper1
    -> index.png
 -> paper2
    -> index.png
 -> paper3
    -> index.png
...

My intention is to build a preview for all papers. So I thought: loop through all available folders and store the complete url in an array. As soon as there is no further folder, stop the loop.

This, however, always ends in an endless-loop. Without using the loop, I get an undefined when I try to print imageArray[0].

Since everything has to run local, I can't use a complete url with http://www

Since ajax is asynchronous, your code is looking for the next file before the call ends. Try adding async : false inside the $.ajax call. — ojovirtual
– ojovirtual, Commented Aug 27, 2015 at 10:20
still runs infinite and doesn't trigger the break-condition. It runs to like paper48, while only 5 folders exists — Saffe
– Saffe, Commented Aug 27, 2015 at 10:25

ojovirtual · Accepted Answer · 2015-08-27 10:33:20Z

1

Synchronous approach:

function lookForFiles(helper, imageArray){
$.ajax({
       url: '/paper' + helper + '/index.png',
       type: 'HEAD',
       statusCode: {
           404: function () {
                console.log('nope');
                return imageArray;
                }
            },
        success: function () {
            console.log('paper' + helper + '/index.png');
            imageArray[helper - 1] = 'paper' + helper + '/index.png';
            helper++;
            lookForFiles(helper,imageArray);
        }
    });
}

var helper = 1;
var imageArray = new Array;
var images = lookForFiles(helper,imageArray);

edited Aug 27, 2015 at 10:33

answered Aug 27, 2015 at 10:25

ojovirtual

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7 Comments

Saffe Over a year ago

Still runs infinite and doesn't stop after folder 5 (folder 6 and up doesn't exist anymore)

Saffe Over a year ago

Updated the question as well. It kinda works already, it just runs afterwards for some reason.

ojovirtual Over a year ago

What version of jQuery are you using?

Saffe Over a year ago

I'm using version 1.11.3

Saffe Over a year ago

It seems like the check if the file exists isn't working properly. It just runs on and on

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