CODEWITHSUNDEEP
javascriptnode.jsfirefoxecmascript-6
user2311517
user2311517

Reputation:

Difference in interpretation between Firefox and Node.js

I have come across an anomaly between Firefox and Node.js. Given the following code:

'use strict';
const obj = {};
for (let f of ['left', 'right']) {
  obj[f] = function() {
    return f;
  };
}
console.log(obj.left());
console.log(obj.right());

Firefox (48.0) outputs

right
right

while Node.js (6.4.0) outputs

left
right

Both on Ubuntu 14.04. I didn't have the possibility to test with other ECMAScript engines.

Any idea what is the reason for the difference, and which implementation is correct with respect to the specification?

Upvotes: 0

Views: 61

Answers (1)

Bergi
Bergi

Reputation: 665316

Your version of Node is correct here, let in a for loop should have block scope.

FF 48 simply doesn't support "for/for-in loop iteration scope" yet, it appears to be fixed with FF 51.

Upvotes: 1

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