This does not work because of the variable rep. What is the correct syntax please?

var bigtext = 'testing test test test';
var rep = 'test'; 
bigtext = bigtext.replace(/rep/g, "MOO!");

I know the problem is with the regex part in the replace...but what is the correct way to write it?

This does not work because of the variable rep. What is the correct syntax please?

var bigtext = 'testing test test test';
var rep = 'test'; 
bigtext = bigtext.replace(/rep/g, "MOO!");

I know the problem is with the regex part in the replace...but what is the correct way to write it?

• javascript
• regex
• replace

• possible duplicate of Using a string variable as regular expression and Pass a variable into regex with string replace. – Felix Kling Commented Aug 14, 2012 at 14:18
• And what has jQuery got to do with basic regular expressions? – epascarello Commented Aug 14, 2012 at 14:18
• @David: epascarello's point was that this has nothing to do with jQuery. Regular expressions are a feature of the language itself. – Felix Kling Commented Aug 14, 2012 at 14:21

1 Answer 1

You need to build a regex using the RegExp constructor:

var bigtext = 'testing test test test';
var rep = 'test'; 
var regex = new RegExp(rep, 'g');
bigtext = bigtext.replace(regex, "MOO!");

Documentation for this constructor can be seen on the MDN page. Note that you probably should make sure that any special characters in regular expressions (e.g. [) are escaped.