[javascript] How can I extract a number from a string in JavaScript?

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.

You can use Underscore String Library as following

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

_(href).strRight(common)

result will be : 1

See :https://github.com/epeli/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>

JS Code :

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

if you have suffix as following :

href="box1az" 

You can use the next demo :

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

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

}

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]);

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 function where you need, with parameter.

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

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');
}

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

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

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

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

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

you may use great parseInt method

it will convert the leading digits to a number

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

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,'');

You can use regular expression.

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

That will alert 2.

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

This answer will cover most of the scenario. I can across this situation when user try 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 a array of string as output >> ["34", "56766"]

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

join will convert and concatenate that array data into single string

output >> "3456766"

In my example I need 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'))
  });

please check below javaScripts, there you can get only number

var txt = "abc1234char5678#!9";_x000D_
var str = txt.match(/\d+/g, "")+'';_x000D_
var s = str.split(',').join('');_x000D_
alert(Number(s));

output : 1234567789

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

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, ''));_x000D_
console.log('#box2'.replace(/[^0-9]/g, ''));

Using match function.

var thenum = thestring.match(/\d+$/)[0];
alert(thenum);

jsfiddle

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

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

jsFiddle:

• http://jsfiddle.net/dmeku/

Tried all the combinations cited above with this Code and got it working, 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 attr but whatever, the solution is better, because its more complete.

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

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

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 wont have it