padStart(2, '0') code example

Example 1: lpad javascript

str.padStart(targetLength [, padString])

Example 2: js number padding to number of characters

var n = 123

String("00000" + n).slice(-5); // returns 00123
("00000" + n).slice(-5); // returns 00123
("     " + n).slice(-5); // returns "  123" (with two spaces)