Ajax upload formdata

var app = {}
app.uploadImage(file) {
        if(window.FormData){
            var formdata = new FormData();
            formdata.append("image_file", file);
            console.debug(file)
        }
        return $.ajax({
            url : "/upload.php",
            type : "POST",
            data: formdata,
            processData : false,
            contentType : false,
            success : function(res) {
                console.debug(res)
            }
        })
    },
$("#id-input").on("change", function(event){
    var file = event.target.files[0];
        if (file !== undefined && window.FileReader !== undefined) {
            var reader = new FileReader();
            var self = this;

            reader.onload = function(e) {
                if (window.Blob) {
                    var blob = new Blob([e.target.result]);
                    window.URL = window.URL || window.webkitURL;
                    var blobURL = window.URL.createObjectURL(blob);
                    //self.setSrc(blobURL);
                    app.uploadImage(file);
                }
            };

            // reader.readAsDataURL(file);
            reader.readAsArrayBuffer(file);
        } else {
            if (!file)
                console.error("No file prevented");
            if (!window.FileReader)
                console.error("Your browser is not supported");
        }
})