I'm writing a JavaScript/PHP file uploader and I want to start this project off on the right track. I've started with this, a JavaScript Uploader object which will handle Ajax calls, display progress, show error messages, etc. I'm just hoping to get some feedback on the way I'm setting up my scripts.

function Uploader(method) {

if(arguments.callee._singleton) return arguments.callee._singleton;
var _this = arguments.callee._singleton = this;

_this.opts = {
errorCodes:{
1:"No file/folder selected",
2:"Invalid file/folder type",
}
}

_this.methods = {

init: function(options) {
for(var o in options) {
_this.opts[o] = options[o];
}

_this.methods.setup();
},

setup: function() {

}

}

if(_this.methods[method]) return _this.methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
else if(typeof method === "object" || !method) return methods.init.apply(this, arguments);

}

-
Can you elaborate on how exactly you'll be using this Uploader object? The _singleton code at the very top and the code at the very bottom (as well as the use of a local _this variable) is confusing. –  seand Jan 30 '12 at 0:31

Why not use an existing ajax file upload library, like Fine Uploader?

I think you meant to return _this.methods.init.apply(this, arguments);.
You should rewrite Uploader to not use arguments.callee for two reasons; it makes your code harder to read and for the browser to optimize.
Not to mention arguments.callee isn't supported in ECMAScript 5. –  bob_cobb Nov 5 '12 at 17:20