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

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

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

jsFiddle:

• http://jsfiddle.net/dmeku/

Answer 11

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 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

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 22

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 23

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 24

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 25

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 26

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 27

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)/');