How to Compare two Arrays are Equal using Javascript?

Question

I want position of the array is to be also same and value also same.

var array1 = [4,8,9,10];
var array2 = [4,8,9,10];

I tried like this

var array3 = array1 === array2   // returns false

Answer 1

You could use Array.prototype.every().(A polyfill is needed for IE < 9 and other old browsers.)

var array1 = [4,8,9,10];
var array2 = [4,8,9,10];

var is_same = (array1.length == array2.length) && array1.every(function(element, index) {
    return element === array2[index]; 
});

THE WORKING DEMO.

Answer 2

A less robust approach, but it works.

a = [2, 4, 5].toString();
b = [2, 4, 5].toString();

console.log(a===b);

Answer 3

var array3 = array1 === array2

That will compare whether array1 and array2 are the same array object in memory, which is not what you want.

In order to do what you want, you'll need to check whether the two arrays have the same length, and that each member in each index is identical.

Assuming your array is filled with primitives—numbers and or strings—something like this should do

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; 
}

Answer 4

A more modern version:

function arraysEqual(a, b) {
  a = Array.isArray(a) ? a : [];
  b = Array.isArray(b) ? b : [];
  return a.length === b.length && a.every((el, ix) => el === b[ix]);
}

Coercing non-array arguments to empty arrays stops a.every() from exploding.

If you just want to see if the arrays have the same set of elements then you can use Array.includes():

function arraysContainSame(a, b) {
  a = Array.isArray(a) ? a : [];
  b = Array.isArray(b) ? b : [];
  return a.length === b.length && a.every(el => b.includes(el));
}

Answer 5

You could try this simple approach

var array1 = [4,8,9,10];
var array2 = [4,8,9,10];

console.log(array1.join('|'));
console.log(array2.join('|'));

if (array1.join('|') === array2.join('|')) {
 console.log('The arrays are equal.');
} else {
 console.log('The arrays are NOT equal.');
}

array1 = [[1,2],[3,4],[5,6],[7,8]];
array2 = [[1,2],[3,4],[5,6],[7,8]];

console.log(array1.join('|'));
console.log(array2.join('|'));

if (array1.join('|') === array2.join('|')) {
 console.log('The arrays are equal.');
} else {
 console.log('The arrays are NOT equal.');
}

If the position of the values are not important you could sort the arrays first.

if (array1.sort().join('|') === array2.sort().join('|')) {
    console.log('The arrays are equal.');
} else {
    console.log('The arrays are NOT equal.');
}

Answer 6

If you comparing 2 arrays but values not in same index, then try this

var array1=[1,2,3,4]
var array2=[1,4,3,2]
var is_equal = array1.length==array2.length && array1.every(function(v,i) { return ($.inArray(v,array2) != -1)})
console.log(is_equal)

Answer 7

Here goes the code. Which is able to compare arrays by any position.

var array1 = [4,8,10,9];

var array2 = [10,8,9,4];

var is_same = array1.length == array2.length && array1.every(function(element, index) {
    //return element === array2[index];
  if(array2.indexOf(element)>-1){
    return element = array2[array2.indexOf(element)];
  }
});
console.log(is_same);

Answer 8

Use lodash. In ES6 syntax:

import isEqual from 'lodash/isEqual';
let equal = isEqual([1,2], [1,2]);  // true

Or previous js versions:

var isEqual = require('lodash/isEqual');
var equal = isEqual([1,2], [1,2]);  // true

Answer 9

function isEqual(a) {
if (arrayData.length > 0) {
    for (var i in arrayData) {
        if (JSON.stringify(arrayData[i]) === JSON.stringify(a)) {
            alert("Ya existe un registro con esta informacion");
            return false;
        }
    }
}
}

Answer 10

Try doing like this: array1.compare(array2)=true

Array.prototype.compare = function (array) {
    // if the other array is a falsy value, return
    if (!array)
        return false;

    // compare lengths - can save a lot of time
    if (this.length != array.length)
        return false;

    for (var i = 0, l=this.length; i < l; i++) {
        // Check if we have nested arrays
        if (this[i] instanceof Array && array[i] instanceof Array) {
            // recurse into the nested arrays
            if (!this[i].compare(array[i]))
                return false;
        }
        else if (this[i] != array[i]) {
            // Warning - two different object instances will never be equal: {x:20} != {x:20}
            return false;
        }
    }
    return true;
}