Question

I need to replace two different characters in a string all instances so i found this answer

<script type="text/javascript">
   var filter_out = eval("/1|3/ig");
   var myvar = "1 2 3";
   alert(myvar.replace(filter_out, "-"));
</script>

// - 2 -

It works, however this one does not:

<script type="text/javascript">
   var filter_out = eval("/\+|\-/ig");
   var myvar="+ 2 -";
   alert(myvar.replace(filter_out, "-"));
</script>

//SyntaxError: invalid quantifier: /+|-/ig

Never mind i fond that it works if i use

var filter_out = eval("/\\+|\\-/ig");

can someone explain why it has to be double \?
Also i know “g” stands for global – all occurances, what “i” stands for?

Answer 1

Don’t use eval, use the RegExp object:

var myvar = '+ 2 -';
alert(myvar.replace(/\+|\-/ig, '-'));

Result: - 2 -

i means it will ignore case.