Add leading zeros (character or string) to number

pad.js

// Pad number i left with c until n characters or more
// padLeft(1, 3); 	// '001'
// padLeft(12, 3);	// '012'
// padLeft(1234, 3);	// '1234'
// padLeft(1, 3, 'x');	// 'xx1'

function padLeft(i, n, c){
    return Array(n - String(i).length + 1).join(c||'0') + i;
}