Extract a number from a string? (Javascript)

Question

var amount = "(21)";

How would I go about just getting the number? I have gotten it to work with...

var amountResult = amount.substring(1, amount.length-1);

...but that just feels incorrect.

What's the better, more flexible way to do this if it were not always surrounded by just 2 characters?

Thanks!

For something that simple I think a couple of trivial string calls are better than an regex. You could also; parseInt(amount.substr(1), 10) — Alex K.
– Alex K., Commented Jan 31, 2014 at 17:47
possible duplicate of how to extract numbers from string using Javascript? and many more. — Felix Kling
– Felix Kling, Commented Jan 31, 2014 at 17:49
Oh so horrible: var amount = "(21)"; var num = new Function("return " + amount + ";")();, but I had to share. — epascarello
– epascarello, Commented Jan 31, 2014 at 17:57
@epascarello well for that matter, var num = eval(amount); -- but yeah, I wouldn't recommend that. — p.s.w.g
– p.s.w.g, Commented Jan 31, 2014 at 19:57

p.s.w.g · Accepted Answer · 2014-01-31 17:47:01Z

4

Using a regular expression is much more flexible:

var amountResult = amount.match(/\d+/)[0];

And to actually turn it into an number:

var amountResult = parseInt(amount.match(/\d+/)[0], 10);

answered Jan 31, 2014 at 17:47

p.s.w.g

150k31 gold badges307 silver badges339 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1