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Index inside map() Function
  • Last Updated : 22 Nov, 2019

In JavaScript, map() method handles array elements, which creates a new array with the help of results obtained from calling function for each and every array element in an array. The index is used inside map() method to state the position of each element in an array, but it doesn’t change the original array.

Syntax:

array.map(function(currentelement, index, arrayobj) {

  // Returns the new value instead of the item

});

Parameters: The Index inside function accepts three parameters as mentioned above and described below:

  • currentelement: The currentelement is a required argument in map() which is the value of current element.
  • index: The index is an optional argument map() which is an array index of provided current element.
  • arrayobj: The arrayobj is an optional argument in map() which is the array object where the current element belongs.

Below examples illustrate the Index inside map() function:

Example 1:






<!DOCTYPE html>
<html lang="en">
  
<head>
    <meta charset="utf-8">
    <meta name="viewport" content=
           "width=device-width, initial-scale=1">
</head>
  
<body style="text-align:center;">
      
    <h1 style="color:green;padding:13px;">
        GeeksforGeeeks
    </h1>
      
    <h3>Index inside map() Function</h3>
      
    <script>
        var student = ["Arun", "Arul", 
            "Sujithra", "Jenifer", "Wilson"];
          
        student.map((stud, index) => {
            alert("Hello... " + stud + "\n");
              
            var index = index + 1;
              
            alert("Your Position in Top 5"
                + " Rank is " + index + "\n");
        });
    </script>
</body>
  
</html>

Output:

Example 2:




<!DOCTYPE html>
<html lang="en">
   
<head>
    <meta charset="utf-8">
      
    <meta name="viewport" content=
        "width=device-width, initial-scale=1">
</head>
   
<body style="text-align:center;">
      
    <h1 style="color:green;padding:13px;">
      GeeksforGeeeks
    </h1>
      
    <h3>Index inside map() Function</h3>
      
    <script>
        var webname = ["welcome", "to",
                    "GeeksforGeeeks"];
          
        webname.map((web, index) => {
            document.write(web + "<br>");
        });
          
        // check in console
        webname.map((web, index)
            => console.log(web, index));
    </script>
</body>
   
</html>

Output:

welcome
0
to
1
GeeksforGeeeks
2

Supported Browsers: The browsers supported by Index inside map() function are listed below:

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



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