JavaScript: String.prototype.substring
str.substring(start, end)
Same as str.slice(start, end)
but if any argument is negative, it is replaced with 0, and if any argument is greater than length, it's replaced by length.
[see String.prototype.slice]
const ss = "abcd"; console.log( ss.substring(1,3) ); // bc console.log( ss.substring(0, ss.length) ); // abcd console.log( ss.substring() ); // abcd console.log( ss.substring(1) ); // bcd console.log( ss.substring(-1) ); // abcd console.log( ss.substring(-2) ); // abcd