How to get nth occurrence of a string in JavaScript ?

The task is to get the nth occurrence of a substring in a string with the help of JavaScript.

Approach 1:

  • First, split the string into sub-strings using split() method by passing index also.
  • Again join the substrings on passed substring using join() method.
  • Returns the index of nth occurrence of string.

Example:In this example, split() and join() method are used to get the index of substring.

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<!DOCTYPE HTML> 
<html
  
<head
    <title
        How to get nth occurrence of
        a string in JavaScript ?
    </title>
</head
  
<body style = "text-align:center;"
      
    <h1 style = "color:green;"
        GeeksForGeeks
    </h1>
      
    <p id = "GFG_UP" style
        "font-size: 19px; font-weight: bold;">
    </p>
      
    <button onclick = "GFG_Fun()">
        click here
    </button>
      
    <p id = "GFG_DOWN" style
        "color: green; font-size: 24px; font-weight: bold;">
    </p>
      
    <script>
        var el_up = document.getElementById("GFG_UP");
        var el_down = document.getElementById("GFG_DOWN");
        var string = "Geeks gfg Geeks Geek Geeks gfg";
        var searchString = 'Geeks';
        var occurrence = 3;
          
        el_up.innerHTML = "Click on the button to get the index of "
                + occurrence + "rd occurrence of a '" + searchString
                + "' in a <br>'" + string + "'.";
          
        function getPos(str, subStr, i) {
            return str.split(subStr, i).join(subStr).length;
        }
        function GFG_Fun() {
            el_down.innerHTML
                    = getPos(string, searchString, occurrence);
        }
    </script
</body>
  
</html>

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Output:

  • Before clicking on the button:
    nth-occurrence-01
  • After clicking on the button:
    nth-occurrence-02

Approach 2: Go through each substring one by one and return the index of the last substring. This approach uses indexOf() method to return the index of nth occurrence of the string.



Example:

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<!DOCTYPE HTML> 
<html
  
<head
    <title
        How to get nth occurrence of
        a string in JavaScript ?
    </title>
</head
  
<body style = "text-align:center;" id = "body"
      
    <h1 style = "color:green;"
        GeeksForGeeks
    </h1>
      
    <p id = "GFG_UP" style
        "font-size: 19px; font-weight: bold;">
    </p>
      
    <button onclick = "GFG_Fun()">
        click here
    </button>
      
    <p id = "GFG_DOWN" style =
        "color: green; font-size: 24px; font-weight: bold;">
    </p>
      
    <script>
        var el_up = document.getElementById("GFG_UP");
        var el_down = document.getElementById("GFG_DOWN");
        var string = "Geeks gfg Geeks Geek Geeks gfg";
        var searchString = 'Geeks';
        var occurrence = 3;
          
        el_up.innerHTML = "Click on the button to get the index of "
                + occurrence + "rd occurrence of a '" + searchString
                + "' in a <br>'" + string + "'.";
          
        function getIndex(str, substr, ind) {
            var Len = str.length, i = -1;
            while(ind-- && i++ < Len) {
                i = str.indexOf(substr, i);
                if (i < 0) break;
            }
            return i;
        }
        function GFG_Fun() {
            el_down.innerHTML 
                    = getIndex(string, searchString, occurrence);
        }
    </script> 
</body>
  
</html>

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Output:

  • Before clicking on the button:
    nth-occurrence-03
  • After clicking on the button:
    nth-occurrence-04

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Improved By : nidhi_biet, Akanksha_Rai