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Extract a number from a string using JavaScript

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  • Difficulty Level : Basic
  • Last Updated : 26 Jul, 2022
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The number from a string in javascript can be extracted into an array of numbers by using the match method. This function takes a regular expression as an argument and extracts the number from the string. Regular expression for extracting a number is (/(\d+)/). 

Example 1: This example uses match() function to extract number from string. 

html




<!DOCTYPE html>
<html>
<head>
    <title>
        Extract number from string
    </title>
</head>
 
<body >
    <div align="center" style="background-color: green;">
         
        <h1>GeeksforGeeks</h1>
         
        <p>String is "jhkj7682834"</p>
         
        <p id="GFG">
            Click the button to extract number
        </p>
         
        <input type="button" value="click " onclick="myGeeks()">
    </div>
     
    <script>
        function myGeeks() {
            var str = "jhkj7682834";
            var matches = str.match(/(\d+)/);
             
            if (matches) {
                document.getElementById('GFG').innerHTML
                        = matches[0];
            }
        }
    </script>
</body>
</html>                               

Output:

  • Before Clicking the button:
  • After Clicking the button:

Example 2: This example uses match() function to extract number from string. 

html




<!DOCTYPE html>
<html>
<head>
    <title>
        Extract number from string
    </title>
</head>
 
<body>
    <div align="center" style="background-color: green;">
         
        <h1>GeeksforGeeks</h1>
         
        <p>String is "foo35bar5jhkj88"</p>
         
        <h3>
            The string contains 3 numbers. So the numbers
            are stored in an array and print together
        </h3>
         
        <p id="GFG">
            Click the button to extract number
        </p><br>
         
        <h3 id="Geeks"></h3>
         
        <input type="button" value="Click Here!" onclick="myGeeks()">
    </div>
     
    <script>
        function myGeeks() {
            var str = "foo35bar5jhkj88";
            matches = str.match(/\d+/g);
            var i=0
         
            document.getElementById('GFG').innerHTML
                = matches[0] + matches[1] + matches[2];
             
            document.getElementById("Geeks").innerHTML
                = "Where 35 is the first, 5 is the second"
                + " and 88 is the third number"
    }
    </script>
</body>
</html>                   

Output:

  • Before Clicking the button:
  • After Clicking the button:

Example#3 : This example uses reduce method to extract all the number from string.

HTML




<!DOCTYPE html>
<html>
<head>
    <title>
        Extract number from string
    </title>
</head>
 
<body >
    <div align="center" style="background-color: green;">
         
        <h1>GeeksforGeeks</h1>
         
         
<p>String is "jhkj7682834"</p>
 
         
        <p id="GFG">
            Click the button to extract number
        </p>
 
         
        <input type="button" value="click " onclick="myGeeks()">
    </div>
     
    <script>
        function myGeeks() {
            var str = "jhkj7682834";
            var c = '0123456789'
             
            function check(x) {
                        return c.includes(x)  ? true : false;
                    }
            var matches = [...str].reduce((x, y) => check(y) ? x+y : x, '')
             
            if (matches) {
                document.getElementById('GFG').innerHTML
                        = matches;
            }
        }
    </script>
</body>
</html>

Output:

  • Before clicking Button:

reduce () function

  • After clicking Button:

reduce() 

JavaScript is best known for web page development but it is also used in a variety of non-browser environments. You can learn JavaScript from the ground up by following this JavaScript Tutorial and JavaScript Examples.


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