nesting-structure-comparison.js

/**
 * http://www.codewars.com/kata/520446778469526ec0000001/
 *
 Description:

 Complete the method (or function in Python) to return true when its argument is an array that has the same nesting structure as the first array.

 For your convenience, there is already a function 'isArray(o)' declared in the JS version that returns true if its argument is an array, false otherwise.
 */

let tests = require('./lib/framework.js');
let Test = tests.Test, describe = tests.describe, it = tests.it, before = tests.before, after = tests.after;

function isArray(ar) {
    return Object.prototype.toString.call(ar) === '[object Array]';
}

function sameStructure(a1, a2) {
    if (!isArray(a1) && !isArray(a2)) return true;
    if (a1.length !== a2.length) return false;

    return a1.every((x, i) => {
        return sameStructure(a1[i], a2[i]);
    });
}

Array.prototype.sameStructureAs = function (other) {
    return sameStructure(this, other);
};

Test.expect([ 1, 1, 1 ].sameStructureAs( [ 2, 2, 2 ] ));
Test.expect([ 1, [ 1, 1 ] ].sameStructureAs( [ 2, [ 2, 2 ] ] ));

Test.expect([ 1, [ 1, 1 ] ].sameStructureAs( [ [ 2, 2 ], 2 ] ) === false);
Test.expect([ 1, [ 1, 1 ] ].sameStructureAs( [ [ 2 ], 2 ] ) === false);

Test.expect([ [ [ ], [ ] ] ].sameStructureAs( [ [ [ ], [ ] ] ] ));
Test.expect([ [ [ ], [ ] ] ].sameStructureAs( [ [ 1, 1 ] ] ) === false);