How to extract number from a string in javascript

parseInt() is pretty sweet.

HTML

<span id="foo">280ms</span>

JS

var text = $('#foo').text();
var number = parseInt(text, 10);
alert(number);

parseInt() will process any string as a number and stop when it reaches a non-numeric character. In this case the m in 280ms. After have found the digits 2, 8, and 0, evaluates those digits as base 10 (that second argument) and returns the number value 280. Note this is an actual number and not a string.

Edit:
@Alex Wayne's comment.
Just filter out the non numeric characters first.

parseInt('ms120'.replace(/[^0-9\.]/g, ''), 10);

Try this:

var num = document.getElementById('spanID').innerText.match(/\d+/)[0];

jQuery version:

var num = $('span').text().match(/\d+/)[0]; // or $('#spanID') to get to the span

If you want as numeric value (and not as string), use parseInt:

var num = parseInt($('span').text().match(/\d+/)[0], 10);

Try the following

var strValue = // get 280m from the span
var intValue = parseInt(strValue.match(/[0-9]+/)[0], 10);