Number constructor issue

[f-xyz]

Babel somehow changes Number constructor behavior. It breaks number comparison in Chai.js assertion library.

Example code: 1.js

'use strict';

var numberObject = new Number(1);

console.log(numberObject);
console.log('\n');

console.log(numberObject.constructor(numberObject));
console.log(Number(numberObject));
console.log(Number.prototype.constructor(numberObject));
console.log('\n');

console.log(typeof numberObject.constructor(numberObject));
console.log(typeof Number(numberObject));
console.log(typeof Number.prototype.constructor(numberObject));
console.log('\n');

console.log(numberObject.constructor === Number);
console.log(numberObject.constructor === Number.prototype.constructor);
console.log('\n');

console.log(Number.toString());
console.log(numberObject.constructor.toString());
console.log('\n');

Output of node 1.js

[Number: 1]


1 // it's a number
1
1


number // it's a number
number
number


true
true


function Number() { [native code] }
function Number() { [native code] }

Output of babel-node 1.js (the same for require('babel/register'))

[Number: 1]


[Number: 1] // it shouldn't be an object
1
1


object // it shouldn't be an object
number
number


true
true


function Number() { [native code] }
function Number() { [native code] }

[zloirock]

Strange. Please, open issue in core-js repo.

[zloirock]

Heh. Problem in constructor detection here. In your strange case this instanceof Number, like in new Number. Need add slow classof Object#toString.call check =\ As I say, please, open issue in core-js repo and it will be fixed in next release.

[f-xyz]

Created issue zloirock/core-js#89