Question

Here is the code :

> var reg = new RegExp(" hel.lo ", 'g');
> 
> var str = " helalo helblo helclo heldlo ";
> 
> var mat = str.match(reg);
> 
> alert(mat);

It alerts “helalo, helclo”, but i expect it to be “helalo, helblo, helclo, heldlo” .
Only the half of them matches, I guess that’s because of the space wich count only once. So I tried to double every space before processing, but in some case it’s not enough.
I’m looking for an explanation, and a solution.

Thx

Answer 1

  "␣helalo␣helblo␣helclo␣heldlo␣"
// 11111111------22222222-------

When ␣helalo␣ was matched, the string left is helblo␣... without the leading space. But the regex requires a leading space, so it skips to ␣helclo␣.

To avoid the expression eating up the space, use a lookahead.

var reg = / hel.lo(?= )/g

(Or use \b as a word boundary.)