How to put variable in regular expression match?

Question

I have the following snippet. I want to find the appearance of a, but it does not work. How can I put the variable right?

var string1 = 'asdgghjajakhakhdsadsafdgawerwweadf'; var string2 = 'a'; string1.match('/' + string2 + '/g').length; 

Answer 1

You need to use the RegExp constructor instead of a regex literal.

var string = 'asdgghjjkhkh'; var string2 = 'a'; var regex = new RegExp( string2, 'g' ); string.match(regex); 

If you didn't need the global modifier, then you could just pass string2, and .match() will create the regex for you.

string.match( string2 );