Finding unique arrays in the most efficient method

Question

I have the following arrays,

var a = [1,2,3,4,5];
var b = [2,3,4,5,6];
var c = [4,5,6,7,8];
var d = [1,2,3,4,5];

What is the most efficient way to find out the arrays that are distinct? I.e array a, b and c are distinct, where the order matters.

• Stephen P: Where you say "the order matters" do you mean that a and d are the same, but var e = [5,4,3,2,1]; would be different, because the same content is in a different order?
• Jorawar Singh: try this very easy a.toString() === b.toString()
• Hitmands: probably interesting: stackoverflow.com/questions/3115982/…
• juvian: The solutions below are valid, a more efficient one would be to do something similar to bucket sort, but doubt you need that much efficiency

Answer 1

One interesting way would be to convert them to String and Compare them. You could JSON stringify them or just join them like this

a.join('') === b.join('')

This works just because you say the order matters. I don't know the benchmarks between using JSON's stringify over join primitive. Maybe you could try that.

Answer 2

This is also can be done like this

a.toString() === b.toString()

• Park Taecyeon: This works, unfortunately, I'm dealing with 20 MB JSON files and it's taking a long time.
• Jorawar Singh: @ParkTaecyeon that's something hard to do anything about then finding a way to make file shorter, it's not a good idea in best practice having a json file of 20 MB. please accept the answer if you find it useful :-)

Answer 3

You can use Array.prototype.every() to compare arrays with Javascript

var a = [1,2,3,4,5];
var b = [2,3,4,5,6];
var is_same = (a.length == b.length) && a.every(function(element, index) {
return element === b[index]; 
});

• dandavis: only type-safe solution presented so far.