Match and replace all tabs at the beginning of the line with four spaces

Question

I\'ve read some other questions and answers on the site, but all of them were a little different from what I\'m seeking: replace all tabs at the beginning of a string with four

Answer 1

^ means "beginning of line", + means "one or more times", m means "multiline" and g means "greedy" (find all occurrences). Finally, there is a little trick to convert one occurrence of n tabs into n dots (I use dots to prove that I don't replace trailing tabs) :

YYY = "YYY";
n = YYY.length;
(new Array(n + 1)).join("X") // "XXX"

var tabs = document.getElementById("tabs");
var dots = document.getElementById("dots");
var text = tabs.textContent;
dots.textContent = text.replace(/^\t+/mg, function ($0) {
  return (new Array($0.length + 1)).join(".");
});

	1 leading tab, 1 trailing tab	
		2 leading tabs, 1 trailing tab	
			3 leading tabs, 1 trailing tab