what-is-this

What value is this in Strict, Script, or Module?

Comparison Table

Open following URL:

• Function: https://azu.github.io/what-is-this
• Method: https://azu.github.io/what-is-this/method.html

Bug

• V8
  • 791334 - this in top level Arrow Function in Module Context should be undefined - chromium - Monorail

Specification

• Set [[ThisValue]]
  • https://tc39.github.io/ecma262/#sec-evaluatecall
  • https://tc39.github.io/ecma262/#sec-call
  • https://tc39.github.io/ecma262/#sec-ecmascript-function-objects-call-thisargument-argumentslist
  • https://tc39.github.io/ecma262/#sec-ordinarycallbindthis
• Lookup [[ThisValue]]
  • https://tc39.github.io/ecma262/#sec-getthisenvironment

Script(Global) Environment

• [[ThisValue]]: global

Module Environment

• [[ThisValue]]: undefiled

Function call

• Depended on call context

Arrow Function call

• Arrow Function don’t bind [[ThisValue]]
• Depended on enclosing environment
• https://tc39.github.io/ecma262/#sec-ordinarycallbindthis
• https://tc39.github.io/ecma262/#sec-arrow-function-definitions-runtime-semantics-evaluation
• https://esdiscuss.org/topic/clarification-regarding-top-level-arrow-functions-and-this-arguments

Changelog

See Releases page.

Running tests

Install devDependencies and Run npm test:

npm i -d && npm test

Contributing

Pull requests and stars are always welcome.

For bugs and feature requests, please create an issue.

1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Submit a pull request :D

Author

• github/azu
• twitter/azu_re

License

MIT © azu