function partial(fn) {	
	var args = Array.prototype.slice.call(arguments);
	var args = args.slice(1);
 
	return function() {
		var args1 = Array.prototype.slice.call(arguments);
 		var newArgs = args.concat(args1);
 		var j = 0;
 		for (var i = 0; i < newArgs.length; i++) {
 			if (newArgs[i] === undefined) {
 				newArgs[i] = arguments[j];
 				j++;
 			};
 		};
 		var x = fn.apply(null, newArgs);
		return x;
	}
}
 
 
function test(a, b, c, d) { return 'a=' + a + ',b=' + b + ',c=' + c + ',d=' + d; }
var test1_3 = partial(test, 1, undefined, undefined, 3);
console.log(test1_3(5, 6)); 
console.log(test1_3(4, 1)); 

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