How to detect array equality in JavaScript?

1. Check the length of both arrays
2. Loop through the first array, compare each variable to the second array.

If 1 and 2 are both the same, your array is equal.

Function to compare objects/arrays:

Looping through true arrays can be achieved through for(var i=0; i<array.length; i++).
Walking through the properties of such an object can be done by for(var i in object).

function recursiveCompare(obj, reference){ if(obj === reference) return true; if(obj.constructor !== reference.constructor) return false; if(obj instanceof Array){ if(obj.length !== reference.length) return false; for(var i=0, len=obj.length; i<len; i++){ if(typeof obj[i] == "object" && typeof reference[j] == "object"){ if(!recursiveCompare(obj[i], reference[i])) return false; } else if(obj[i] !== reference[i]) return false; } } else { var objListCounter = 0; var refListCounter = 0; for(var i in obj){ objListCounter++; if(typeof obj[i] == "object" && typeof reference[i] == "object"){ if(!recursiveCompare(obj[i], reference[i])) return false; } else if(obj[i] !== reference[i]) return false; } for(var i in reference) refListCounter++; if(objListCounter !== refListCounter) return false; } return true; //Every object and array is equal } 

If you don't understand the function, feel free to request an explanation at the comments.

With Javascript, you can't check if arrays are equals, but you can compare them like this:

var arr1 = ['alcohol', 'soft', 'hot'], arr2 = ['apple', 'pear'], arr3 = ['soft', 'hot', 'alcohol']; function isSame(a1, a2){ return !(a1.sort() > a2.sort() || a1.sort() < a2.sort()); } console.log( isSame(arr1, arr2) ); //false console.log( isSame(arr1, arr3) ); //true 

The sort put all elements in the same order, and if both < and > comparisons are false it means both are the same.

You can try this JSON.stringify(array1)===JSON.stringify(array2); if you want the order also to be identical in both the arrays.

Does this answer your question? How to check if two arrays are equal with JavaScript?

var equal = array1.compareArrays(array2);