readAsBinaryStringPolyfill for internet explorer

readAsBinaryStringPolyfill.js

/*
  This polyfil is probably incomplete, I made this just to use localforage on internet explorer.
  This polyfill is tested only with this library and works well, but I don't know if it will work i other cases.
  This polyfill is based on this code: https://github.com/nolanlawson/blob-util/blob/4ae6c7a14d3240d977bbdab9ae2f0bb8905ecc37/lib/index.js#L123-L141
*/

if (window.FileReader){
    if(typeof FileReader.prototype.readAsBinaryString !== 'function'){
        console.log("Warning: Using readAsBinaryString polyfill");
        FileReader.prototype.readAsBinaryString = function(blb){
            var reader = new FileReader();
            var that = this;
            var conversor = function (e) {
                var toConvert = e.target.result || '';
                var binary = '';
                var bytes = new Uint8Array(toConvert);
                var length = bytes.byteLength;
                var i = -1;
                while (++i < length) {
                    binary += String.fromCharCode(bytes[i]);
                }
                var f = {};
                for (var property in e) {
                    if (property != "target"){
                        f[property] = e[property];
                    }
                }
                f.target = {};
                for (var property in e.target) {
                    if (property != "result"){
                        f.target[property] = e.target[property];
                    }
                }
                f.target.result = binary;
                that.onloadend(f);
            };
            if (!(this.onloadend === undefined || this.onloadend === null)){
                reader.onloadend = conversor;
            };
            if (!(this.onerror === undefined || this.onerror === null)){
                reader.onerror = this.onerror;
            };
            if (!(this.onabort === undefined || this.onabort === null)){
                reader.onabort = this.onabort;
            };
            if (!(this.onloadstart === undefined || this.onloadstart === null)){
                reader.onloadstart = this.onloadstart;
            };
            if (!(this.onprogress === undefined || this.onprogress === null)){
                reader.onprogress = this.onprogress;
            };
            if (!(this.onload === undefined || this.onload === null)){
                reader.onload = conversor;
            };
            //abort not implemented !!!
            reader.readAsArrayBuffer(blb);
        }
    }
}