Extract a number from a string (JavaScript)

Question

I have a string in JavaScript like #box2 and I just want the 2 from it.

I tried:

var thestring = $(this).attr(\'href\');
var          


        

Answer 1

Try the following: string.replace(/[^0-9]/g, ''); This will delete all non-digit characters, leaving only digits in the string

function retnum(str) { 
    var num = str.replace(/[^0-9]/g, ''); 
    return parseInt(num,10); 
}

console.log('abca12bc45qw'.replace(/[^0-9]/g, ''));
console.log('#box2'.replace(/[^0-9]/g, ''));

Answer 2

Here's a solt. that checks for no data

var someStr = 'abc'; // add 123 to string to see inverse

var thenum = someStr.match(/\d+/);

if (thenum != null )
{
    console.log(thenum[0]);
}
else
{
 console.log('no number');
}

Answer 3

For this specific example,

 var thenum = thestring.replace( /^\D+/g, ''); // replace all leading non-digits with nothing

in the general case:

 thenum = "foo3bar5".match(/\d+/)[0] // "3"

Since this answer gained popularity for some reason, here's a bonus: regex generator.

function getre(str, num) {
  if(str === num) return 'nice try';
  var res = [/^\D+/g,/\D+$/g,/^\D+|\D+$/g,/\D+/g,/\D.*/g, /.*\D/g,/^\D+|\D.*$/g,/.*\D(?=\d)|\D+$/g];
  for(var i = 0; i < res.length; i++)
    if(str.replace(res[i], '') === num) 
      return 'num = str.replace(/' + res[i].source + '/g, "")';
  return 'no idea';
};
function update() {
  $ = function(x) { return document.getElementById(x) };
  var re = getre($('str').value, $('num').value);
  $('re').innerHTML = 'Numex speaks: <code>' + re + '</code>';
}

<p>Hi, I'm Numex, the Number Extractor Oracle.
<p>What is your string? <input id="str" value="42abc"></p>
<p>What number do you want to extract? <input id="num" value="42"></p>
<p><button onclick="update()">Insert Coin</button></p>
<p id="re"></p>

Answer 4

You need to add "(/\d+/g)" which will remove all non-number text, but it will still be a string at this point. If you create a variable and "parseInt" through the match, you can set the new variables to the array values. Here is an example of how I got it to work:

    var color = $( this ).css( "background-color" );
    var r = parseInt(color.match(/\d+/g)[0]);
    var g = parseInt(color.match(/\d+/g)[1]);
    var b = parseInt(color.match(/\d+/g)[2]);

Answer 5

You should try the following:

var txt = "#div-name-1234-characteristic:561613213213";
var numb = txt.match(/\d/g);
numb = numb.join("");
alert (numb);​

result

1234561613213213

Answer 6

With Regular Expressions, how to get numbers from a String, for example:

String myString = "my 2 first gifts were made by my 4 brothers";
myString = myString .replaceAll("\\D+","");
System.out.println("myString : " + myString);

the result of myString is "24"

you can see an example of this running code here: http://ideone.com/iOCf5G