How to know if two arrays have the same values in JavaScript?

In JavaScript, comparing arrays directly with == or === compares references, not values. To check if two arrays contain the same values (regardless of order), we need custom comparison logic.

The Problem with Direct Comparison

var firstArray = [100, 200, 400];
var secondArray = [400, 100, 200];

console.log(firstArray === secondArray);  // false
console.log([1, 2] === [1, 2]);          // false - different objects

false
false

Using Sort and Compare Method

The most reliable approach is to sort both arrays and compare each element:

var firstArray = [100, 200, 400];
var secondArray = [400, 100, 200];

function areBothArraysEqual(firstArray, secondArray) {
    if (!Array.isArray(firstArray) || !Array.isArray(secondArray) ||
        firstArray.length !== secondArray.length)
        return false;
    
    var tempFirstArray = firstArray.concat().sort();
    var tempSecondArray = secondArray.concat().sort();
    
    for (var i = 0; i 

Both are equals


Using JSON.stringify() Method

For simple arrays, you can convert sorted arrays to strings and compare:

function compareArraysWithJSON(arr1, arr2) {
    if (arr1.length !== arr2.length) return false;
    return JSON.stringify(arr1.sort()) === JSON.stringify(arr2.sort());
}

var firstArray = [100, 200, 400];
var secondArray = [400, 100, 200];

console.log(compareArraysWithJSON(firstArray, secondArray));  // true

var thirdArray = [100, 200, 500];
console.log(compareArraysWithJSON(firstArray, thirdArray));   // false


true
false


Comparison of Methods

Key Points

• Direct array comparison with === compares references, not values
• Always check array lengths first for performance
• Use concat() to avoid modifying original arrays when sorting
• The sort-and-compare method works reliably for primitive values

Conclusion

The sort-and-compare method is the most reliable way to check if arrays contain the same values. Use JSON.stringify() for simple cases, but prefer explicit comparison for better control and performance.