How to find a number in a string using JavaScript?

Question

Suppose I have a string like - "you can enter maximum 500 choices". I need to extract 500 from the string.

The main problem is the String may vary like "you can enter maximum 12500 choices". So how to get the integer part?

Answer 1

Use a regular expression.

var r = /\d+/; var s = "you can enter maximum 500 choices"; alert (s.match(r)); 

The expression \d+ means "one or more digits". Regular expressions by default are greedy meaning they'll grab as much as they can. Also, this:

var r = /\d+/; 

is equivalent to:

var r = new RegExp("\d+"); 

See the details for the RegExp object.

The above will grab the first group of digits. You can loop through and find all matches too:

var r = /\d+/g; var s = "you can enter 333 maximum 500 choices"; var m; while ((m = r.exec(s)) != null) {   alert(m[0]); } 

The g (global) flag is key for this loop to work.