To generate a four digit number that doesn't repeat in each digit.

randomNumGen.js

var nums = new Array();
for (var i=0;i<10;i++){
	nums.push(i);
}
var outputs = [0,0,0,0];
for (var j=0;j<4;j++){
	var idx = (Math.random() * nums.length) | 0;
	outputs[j] = nums[idx];
	nums.splice(idx,1);
}