CODEWITHSUNDEEP
javascriptnode.jsmodule
mathk
mathk

Reputation: 8143

module.export behave oddly

There is a surprising behaviour with module.exports. The following code:

module.exports = { test: 4};
module.exports.testMe = () => {console.log(this.test);};

Will output undefined. But:

module.exports.test = 4;
module.exports.testMe = () => {console.log(this.test);};

Will output 4. Why does it behave differently?

Upvotes: 0

Views: 29

Answers (1)

mscdex
mscdex

Reputation: 106736

The reason has to do with how arrow functions work, they bind to this (much like if you had used .testMe = fn.bind(this);).

In the first case, you're overwriting module.exports, but this still points to the old object. So when testMe() is implicitly bound to this, you get undefined because there was no test property on the original module.exports.

In the second case, you're not overwriting module.exports, so module.exports === this and testMe() is implicitly bound to this and outputs '4' as expected because both point to the same object, where test exists.

Upvotes: 1

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