js remove first digit from number code example

Example 1: javascript delete first character in string

var oldStr ="Hello";
var newStr = oldStr.substring(1); //remove first character "ello"

Example 2: javascript remove first character from string

let str = 's';

str = (function f(s) { // don't use on large strings
  		return s.length<=1?'':f(s.slice(0, -1))+s[s.length-1]
	})(str); // ""