javascript compare 2 arrays code example

Example 1: how to compare two arrays and return the missing values

var a1 = [1,2,3,4,5,6];
var a2 = [1,3,5];

var absent = a1.filter(e=>!a2.includes(e));

console.log(absent);

Example 2: javascript compare arrays

Array.prototype.equals = function(arr2) {
  return (
    this.length === arr2.length &&
    this.every((value, index) => value === arr2[index])
  );
};

[1, 2, 3].equals([1, 2, 3]);	// true
[1, 2, 3].equals([3, 6, 4, 2]);	// false

Example 3: best way compare arrays javascript

// To compare arrays (or any other object):
// Simple Array Example:
const array1 = ['potato', 'banana', 'soup']
const array2 = ['potato', 'orange', 'soup']

array1 === array2;
// Returns false due to referential equality
JSON.stringify(array1) === JSON.stringify(array2);
// Returns true 


// Another Example:
const deepArray1 = [{test: 'dummy'}, [['woo', 'ya'], 'weird']]
const deepArray2 = [{test: 'dummy'}, [['woo', 'ya'], 'weird']]

deepArray1 === deepArray2;
// Returns false due to referential equality
JSON.stringify(deepArray1) === JSON.stringify(deepArray2);
// Returns true

Example 4: javascript Compare two arrays regardless of order

const isEqual = (a, b) => JSON.stringify(a) === JSON.stringify(b);

// Examples
isEqual([1, 2, 3], [1, 2, 3]);      // true
isEqual([1, 2, 3], [1, '2', 3]);    // false

Example 5: how to compare two arrays javascript

function arraysAreIdentical(arr1, arr2){
    if (arr1.length !== arr2.length) return false;
    for (var i = 0, len = arr1.length; i < len; i++){
        if (arr1[i] !== arr2[i]){
            return false;
        }
    }
    return true; 
}

Example 6: compare arrays javascript

// For regular 1D array
const array1 = [1,2,3,4]
const array2 = [1,2,3,4]

array1.join() === array2.join()
// '1,2,3,4' === '1,2,3,4'

// For anything more complex
const array3 = [1,2,3,[1,2,3]]
const array4 = [1,2,3,[1,2,3]]

JSON.stringify(array3) === JSON.stringify(array4)