API Name: global.StringPolyfill

var StringPolyfill;

if (!String.prototype.padStart) {
/**
* Pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start (left) of the current string
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart
*/

String.prototype.padStart = function padStart(targetLength, padString) {
targetLength = targetLength >> 0; //truncate if number, or convert non-number to 0;
padString = String(typeof padString !== 'undefined' ? padString : ' ');
if (this.length >= targetLength) {
return String(this);
} else {
targetLength = targetLength - this.length;
if (targetLength > padString.length) {
padString += padString.repeat(targetLength / padString.length); //append to original to ensure we are longer than needed
}
return padString.slice(0, targetLength) + String(this);
}
};
}