It's much worse than that. String.prototype.padStart has been available in Node since 8.0, and browsers for a long time. It's not in IE but polyfills are common

It's much worse than that. String.prototype.padStart has been available in Node since 8.0, and browsers for a long time. It's not in IE but polyfills are common. If your first thought is a library, whether you wrote it yourself or not, then you're doing JS badly.