JavaScript - check if array contains all elements of another array

In this article, we would like to show you how to check if an array contains all elements of another array in JavaScript.

Practical example

In this example, we create a function that takes in two arguments:

1. array - the array we want to check whether it has specific elements,
2. target - an array of elements that the tested array must have.

// ONLINE-RUNNER:browser;

const array1 = [1, 2, 3];
const array2 = [1, 2, 3, 4];
const array3 = [1, 2];

const checkElements = (array, target) => target.every((element) => array.includes(element));

console.log(checkElements(array2, array1)); // true
console.log(checkElements(array3, array1)); // false

Explanation:

The checkElements() function uses two methods:

1. every() method - to test whether all elements in the target array pass the test implemented by the provided function,
2. includes() method - to check whether the array includes a certain element.

Optimal solution

// ONLINE-RUNNER:browser;

const checkElements = (array, target) => {
    const guardian = new Set();
    for (const entry of target) {
        guardian.add(entry);
    }
    let count = 0;
    for (const entry of array) {
        if (guardian.has(entry)) {
            count += 1;
        }
    }
    return count === guardian.size;
};


// Usage example:

const array1 = [1, 2, 3];
const array2 = [1, 2, 3, 4];
const array3 = [1, 2];

console.log(checkElements(array2, array1));  // true   // checking if array2 contains array1 elements 
console.log(checkElements(array3, array1));  // false  // checking if array3 contains array1 elements 

See also

1. JavaScript - check if array contains any element of another array

References

1. Array.prototype.every() - JavaScript | MDN
2. Array.prototype.includes() - JavaScript | MDN