JavaScript replace() uppercase or lowercase

Question

I want to use this function but preserving the uppercase or lowercase so for example having something like

var value = 'Replace a string';

var search = 'replace';

value.replace(search, "<span style='font-weight: bold'>"+search+'<span>');

And the output of value be:

Replace a string

Answer 1

Since you're leaving the word itself as-is, you can use a simple regex:

var value = 'Replace a string';
var search = /replace/i;
value = value.replace(search, "<span style='font-weight: bold'>$&</span>");

The $& indicates the matched pattern.