Check if Array has all Elements of Another Array - JavaScript

Check if Array has all Elements of Another Array - Array.includes #

To check if a javascript array contains all of the elements of another array:

1. Call the Array.every method on the first array, passing it a function
2. The function should check if each element is included in the second array
3. If the check is successful for all elements, the Array.every method will return true

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// Not Supported in IE 9-11
const arr1 = ['pizza', 'cola'];
const arr2 = ['pizza', 'cake', 'cola'];

const containsAll = arr1.every(element => {
  return arr2.includes(element);
});

console.log(containsAll); // 👉️ true

The function we pass to the Array.every method is invoked with each element of the array and should return a truthy or falsy value.

If all invocations of the callback function return a truthy value, then the Array.every method returns true, otherwise false is returned.

If the callback function we passed to the Array.every method returns a falsy value, then Array.every also returns false.

Check if Array has all Elements of Another Array - Array.indexOf #

To check if a javascript array contains all of the elements of another array:

1. Call the Array.every method on the first array, passing it a function
2. The function should check if the index of each element is found in the second array
3. If the check is successful for all elements, the Array.every method will return true

Copied!
// Supported in IE 9-11
const arr1 = ['pizza', 'cola'];
const arr2 = ['pizza', 'cake', 'cola']

const containsAll = arr1.every(element => {
  return arr2.indexOf(element) !== -1;
});

console.log(containsAll); // 👉️ true

In the code snippet, we've used the Array.every method to iterate over each element of the first array and check if it is contained in the second array.

The Array.indexOf method searches for a value in the array and returns it's index if the value is contained in the array, otherwise returns -1.