How can I extract a number from a string in JavaScript?

Question

I have a string in JavaScript (e.g., #box2), and I just want the 2 from it.

I tried:

var thestring = $(this).attr('href');
var thenum = thestring.replace(/(^.+)(\w\d+\w)(.+$)/i, '$2');
alert(thenum);

It still returns #box2 in the alert. How can I get it to work?

It needs to accommodate for any length number attached on the end.

Answer 1

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"

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 2

You should try the following:

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

Answer 3

I think this regular expression will serve your purpose:

var num = txt.replace(/[^0-9]/g, '');

Where txt is your string.

It basically rips off anything that is not a digit.

I think you can achieve the same thing by using this as well:

var num = txt.replace(/\D/g, '');

Answer 4

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 5

Using the match function.

var thenum = "0a1bbb2".match(/\d+$/)[0];
console.log(thenum);

Answer 6

And this is a snippet which extracts prices with currency and formatting:

var price = "£1,739.12";
parseFloat(price.replace(/[^\d\.]*/g, '')); // 1739.12

Answer 7

I tried all the combinations cited in the previous answer with this code and got it working. It was the only one that worked on that string → (12) 3456-7890

var str = "(12) 3456-7890";
str.replace(/\D+/g, '');

Result: "1234567890"

Obs: I know that a string like that will not be on the attribute, but whatever, the solution is better, because it’s more complete.

Answer 8

You may use the great parseInt() method.

It will convert the leading digits to a number:

parseInt("-10px");
// Will give you -10

Answer 9

You can extract numbers from a string using a regex expression:

let string = "xxfdx25y93.34xxd73";
let res = string.replace(/\D/g, "");
console.log(res);

Output: 25933473

Wrap it into a vanilla JavaScript function:

function onlyNumbers(text){
    return text.replace(/\D/g, "");
}

Answer 10

function justNumbers(string)
{
   var numsStr = string.replace(/[^0-9]/g, '');
   return parseInt(numsStr);
}

console.log(justNumbers('abcdefg12hijklmnop'));

You can do a function like this

function justNumbers(string)
{
    var numsStr = string.replace(/[^0-9]/g, '');
    return parseInt(numsStr);
}

Remember: if the number has a zero in front of it, the int won’t have it

Answer 11

For a string such as #box2, this should work:

var thenum = thestring.replace(/^.*?(\d+).*/,'$1');

jsFiddle:

• http://jsfiddle.net/dmeku/

Answer 12

To return an int from the string, you can do the following code. It removes all not number characters and returns an integer.

Number("strin[g]3".replace(/\D+/g, ""))

Answer 13

If you want to parse a number from a price like $6,694.20, it can be done this way:

parseFloat('$6,694.20'.replace(/^\D|,+/g, ''))

Or via a function:

function parsePrice(value) {
  return parseFloat(value.replace(/^\D|,+/g, ''))
}

parsePrice('$6,694.20') // 6694.2

Answer 14

let str = "Total Work Duration: 189.56 Hrs.Present: 23.5 Absent: 2";

/* The provided regex globally matches the character
   "." and a digit from the string */
let numArr = str.match(/[\d\.]+/g)

/* It returns an array [189.56, ., 23.5, 2], and
   uses the filter function to remove the '.' */
numArr = numArr.filter(n => n != '.')
console.log(numArr)

Answer 15

You can use a regular expression.

var txt="some text 2";
var numb = txt.match(/\d/g);
alert (numb);

That will alert 2.

Answer 16

If someone need to preserve dots in extracted numbers:

var some = '65,87 EUR';
var number = some.replace(",",".").replace(/[^0-9&.]/g,'');
console.log(number); // returns 65.87

Answer 17

You can use Underscore.js' string library as follows:

var common = "#box"
var href = "#box1"

_(href).strRight(common)

The result will be: 1

See: Underscore.string

Demo:

http://jsfiddle.net/abdennour/Vyqtt/

HTML code:

<p>
    <a href="#box1" >img1</a>
    <a href="#box2" >img2</a>
    <a href="#box3" >img3</a>
    <a href="#box4" >img4</a>
</p>
<div style="font-size:30px"></div>

JavaScript code:

var comm = "#box"
$('a').click(function() {
  $('div').html(_($(this).attr('href')).strRight(comm))})

If you have a suffix as follows:

href="box1az"

You can use the following demo:

http://jsfiddle.net/abdennour/Vyqtt/1/

function retrieveNumber(all, prefix, suffix) {
  var left = _(all).strRight(prefix);
  return _(left).strLeft(suffix);
}

Answer 18

Here's a solution that checks for no data:

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

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

if (thenum != null)
{
    console.log(thenum[0]);
}
else
{
    console.log('Not a number');
}

Answer 19

Please check the below JavaScript code. There you can get only a number.

var txt = "abc1234char5678#!9";
var str = txt.match(/\d+/g, "") + '';
var s = str.split(',').join('');
alert(Number(s));

Output: 1234567789

Answer 20

var elValue = "-12,erer3  4,-990.234sdsd";

var isNegetive = false;
if(elValue.indexOf("-") == 0)
    isNegetive = true;

elValue = elValue.replace( /[^\d\.]*/g, '');
elValue = isNaN(Number(elValue)) ? 0 : Number(elValue);

if(isNegetive)
    elValue = 0 - elValue;

alert(elValue); // -1234990.234

Answer 21

Use this one-line code to get the first number in a string without getting errors:

var myInt = parseInt(myString.replace(/^[^0-9]+/, ''), 10);

Answer 22

Written without a regular expression:

// Without Regex

function extractNumber(string) {
  let numArray = string.split('').map(item => {
    if (typeof +item === 'number' && !isNaN(+item)) 
      return +item
  })
  return +numArray.join('')
}

extractNumber('@1200milion$')  // 1200

Answer 23

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 24

This answer will cover most of the scenarios. I came across this situation when a user tried to copy paste the phone number.

$('#help_number').keyup(function() {
  $(this).val().match(/\d+/g).join("")
});

Explanation:

str = "34%^gd 5-67 6-6ds"

str.match(/\d+/g)

It will give an array of strings as output:

["34", "56766"]

 

str.match(/\d+/g).join("")

join() will convert and concatenate that array data into a single string.

Output:

"3456766"

In my example, I needed the output as 209-356-6788, so I used replace():

$('#help_number').keyup(function() {
  $(this).val($(this).val().match(/\d+/g).join("").replace(/(\d{3})\-?(\d{3})\-?(\d{4})/, '$1-$2-$3'))
});

Answer 25

In one of my projects I had to take a rating value from a string. This is what I used:

let text = '#xbox2'
let num = text.trim().
  split('').
  map(num => Number(num)).
  filter(x => Number.isInteger(x))

Answer 26

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 at http://ideone.com/iOCf5G.

Answer 27

There are multiple ways.

// Using match, match all the digits
'#box2'.match(/\d+/g).join('')

// Using replace, remove everything other than digits
'#box2'.replace(/[^\d]+/g, '')

// Using slice
'#box2'.slice(4)

Answer 28

Use:

changeStrangeDate(dateString: string) {
  var sum = 0;
  var numbers = dateString.match(/\d+/g);
  if (numbers.length > 1) {
    numbers.forEach(element => {
        sum += parseInt(element);
      }
    );
  }
  console.log(new Date(sum).toDateString());
  return new Date(sum).toUTCString();
}

You can do it like that and then call a function where you need it, with a parameter.

this.changeStrangeDate('/Date(1551401820000-0100)/');