JavaScript | RegExp ? Quantifier

The m? Quantifier in JavaScript is used to find the match of any string that contains zero or one occurences of m.

Syntax:

/m?/ 

or

new RegExp("m?")

Syntax with modifiers:

/\m?/g 

or

new RegExp("m?", "g")

Example 1: This example matches the word e followed by zero or one occurrences of k.

filter_none

edit
close

play_arrow

link
brightness_4
code

<!DOCTYPE html>
<html>
  
<head>
    <title>
        JavaScript RegExp ? Quantifier
    </title>
</head>
  
<body style="text-align:center">
      
    <h1 style="color:green">
        GeeksforGeeks
    </h1>
      
    <h2>RegExp ? Quantifier</h2>
      
    <p>Input String: GeeksforGeeks@_123_$</p>
      
    <button onclick="geek()">
        Click it!
    </button>
      
    <p id="app"></p>
      
    <script>
        function geek() {
            var str1 = "GeeksforGeeks@_123_$";
            var regex4 = /ek?/gi;
            var match4 = str1.match(regex4);
  
            document.getElementById("app").innerHTML
                    = "Found " + match4.length
                    + " matches: " + match4;
        }
    </script>
</body>
  
</html>                    

chevron_right


Output:
Before Clicking the button:
plus
After Clicking the button:
plus

Example 2: This example replaces the word 1 followed by zero or one occurrences of 2 with “@”.

filter_none

edit
close

play_arrow

link
brightness_4
code

<!DOCTYPE html>
<html>
  
<head>
    <title>
        JavaScript RegExp ? Quantifier
    </title>
</head>
  
<body style="text-align:center">
      
    <h1 style="color:green">
        GeeksforGeeks
    </h1>
      
    <h2>RegExp ? Quantifier</h2>
      
    <p>String: Geeky#12$#1</p>
      
    <button onclick="geek()">
        Click it!
    </button>
      
    <p id="app"></p>
      
    <script>
        function geek() {
            var str1 = "Geeky#12$#1";
            var regex4 = new RegExp("#12?", "gi");         
            var replace = "@";
            var match4 = str1.replace(regex4, replace);
            document.getElementById("app").innerHTML = 
                " New string: " + match4;
        }
    </script>
</body>
  
</html>                    

chevron_right


Output:
Before Clicking the button:
plus
After Clicking the button:
plus

Supported Browsers: The browsers supported by RegExp ? Quantifier are listed below:

  • Google Chrome
  • Apple Safari
  • Mozilla Firefox
  • Opera
  • Internet Explorer


My Personal Notes arrow_drop_up


If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :

Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.