Determining whether two arrays are equal.

Author: Hemanth HM

Champions: Jordan Harband & Hemanth HM


Today we don't have straightforward way to check if two arrays are equal, it get more messier to check when they are deeply nested arrays.

How is this currently handled?

There is no standard way to do it, there are few modules like array-equal, deep-equal with like 5M and 8M downloads per week respectively, which is subset of deep comparison.

Consider few examples:

// Schema validation
const equal = require('deep-equal');

const expectedSchema = {
  name: {
    type: String,
    required: true
  score: {
    type: Number,
    default: 0

equal(schemaCall.args[0], expectedSchema);

node builtin:

// assert.deepStrictEqual(actual, expected[, message])

deepStrictEqual([new Uint32Array([1, 2, 3, 4]).subarray(1, 3), new Uint32Array([2, 3])]);
// assert.deepEqual(actual, expected[, message])

assert.deepEqual( tokenizer( "AD", "G", cldr ), [{
        type: "G",
        lexeme: "AD",
        value: "1"
    }] );


Have a Array.prototype.equals method, they might look like:

[1,2,3].equals([1,2,3]) // evaluates to true

[1,2,undefined].equals([1,2,3]) // evaluates to false.
[1, [2, [3,4]]].equals([1, [2, [3,4]]]) // true
  foo: 'bar'
}, {
  foo: 'baz'
    foo: 'bar'
}] // false

How are other langugaes handling this?

Ruby: array1.to_set == array2.to_set

Python: [1,[2,3]] == [1,[2,3]]

Java: java.util.Arrays.equal

C#: Enumerable.Except or SequenceEqual