How to check whether an array is subset of another array using JavaScript ?

Last Updated : 09 May, 2020

The task is to check whether an array is a subset of another array with the help of JavaScript. Here are a few techniques discussed.
Approach 1:

This approach checks whether every element of the second array is present in the first array or not.

Example 1: This example uses the approach as discussed above.

<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        check whether an array is 
      subset of another array using JavaScript
    </title>
</head>
  
<body style="text-align:center;">
    <h1 style="color:green;">  
            GeeksForGeeks  
        </h1>
    <p id="GFG_UP" 
       style="font-size: 15px;
              font-weight: bold;">
    </p>
    <button onclick="GFG_Fun()">
        click here
    </button>
    <p id="GFG_DOWN" 
       style="color:green;
              font-size: 20px;
              font-weight: bold;">
    </p>
    <script>
        var up = document.getElementById('GFG_UP');
        var down = document.getElementById('GFG_DOWN');
        var arr1 = ["GFG", "Geeks", "Portal", "Geek", "GFG_1", "GFG_2"];
        var arr2 = ["GFG", "Geeks", "Geek"];
        up.innerHTML = 
          "Click on the button to check the subset property."+
          "<br>Array1-" + arr1 + "<br>Array2-" + arr2;
  
        function GFG_Fun() {
            res = arr2.every(function(val) {
                return arr1.indexOf(val) >= 0;
            });
            not = "";
            if (!res) {
                not = "not";
            }
            down.innerHTML = 
              "Array_2 is " + not + " the subset of Array_1";
        }
    </script>
</body>
  
</html>

Output:

Before clicking on the button:
After clicking on the button:

Approach 2:

This approach declares false if some element of second array is not present in first array.

Example 2: This example uses the approach as discussed above.

<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        check whether an array is subset 
      of another array using JavaScript
    </title>
</head>
  
<body style="text-align:center;">
    <h1 style="color:green;">  
            GeeksForGeeks  
        </h1>
    <p id="GFG_UP" 
       style="font-size: 15px;
              font-weight: bold;">
    </p>
    <button onclick="GFG_Fun()">
        click here
    </button>
    <p id="GFG_DOWN" 
       style="color:green;
              font-size: 20px; 
              font-weight: bold;">
    </p>
    <script>
        var up = document.getElementById('GFG_UP');
        var down = document.getElementById('GFG_DOWN');
        var arr1 = ["GFG", "Geeks", "Portal", "Geek", "GFG_1", "GFG_2"];
        var arr2 = ["GFG", "Geeks", "GeekForGeeks"];
        up.innerHTML = "Click on the button to check the subset property."+
          "<br>Array1-" + arr1 + "<br>Array2-" + arr2;
  
        function GFG_Fun() {
            res = !arr2.some(val => arr1.indexOf(val) === -1);
            not = "";
            if (!res) {
                not = "not";
            }
            down.innerHTML = "Array_2 is " 
            + not + " the subset of Array_1";
        }
    </script>
</body>
  
</html>

Output:

Before clicking on the button:
After clicking on the button:

My Personal Notes

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