What is the best solution for uploading many files using javascript?

My site uploads multiple images all at once, which leads to eternal loading duration for my php files. Now I want to try to split the files from and upload all images seperate, so I can show a process bar and not a loading php for 10 minutes.

First I tried to get the files using FileList. But I am not able to add the seperated files onto the input tag inner the iframe, because of security reasons.

My next attempt would be FormData objects, but I dissuade from using these, because of bad browser support.

Do you have any suggestions for a more pleasent way to upload files?

Code using FileList

 <input type="file" id="gallery" multiple="true" />
    <script defer="true">
        var pullfiles=function(){ 
    // love the query selector
    var fileInput = document.getElementById("gallery");
    var files = fileInput.files;
    // cache files.length 
    var fl = files.length;
    var i = 0;

    while ( i < fl) {
        // localize file var in the loop
        var file = files[i];
        var ip = document.createElement("input");
                ip.setAttribute("type", "file");
                ip.value = file; //generates security error
                document.body.appendChild(ip);
        i++;
    }    
}

// set the input element onchange to call pullfiles
    document.getElementById("gallery").onchange=pullfiles;

//made by Mozilla as an example for FileList Objects -> https://developer.mozilla.org/en-US/docs/Web/API/FileList#Example
        </script>