Initial version of manual bind to arrow function

[vjeux]

This converts the manual bind to an arrow property initializer function.

It works for the base case this.method = this.method.bind(this);, two other patterns that I've seen in the codebase that should be codemodded as well in a subsequent version

• (this: any).method = this.method.bind(this)
• const self = (this: any); self.method = this.method.bind(this)

Test Plan:
npm t

I haven't tried it on the codebase yet, just want to get early feedback

[keyz]

I think you can replace the above with

 root .find(j.MethodDefinition, { kind: 'constructor', }) .find(j.AssignmentExpression, { left: { type: 'MemberExpression', object: { type: 'ThisExpression', }, property: { type: 'Identifier', }, }, right: { type: 'CallExpression', callee: { type: 'MemberExpression', property: { type: 'Identifier', name: 'bind', }, object: { type: 'MemberExpression', object: { type: 'ThisExpression', }, property: { type: 'Identifier', }, }, }, }, }) .filter(path => path.node.left.property.name === path.node.right.callee.object.property.name )

[vjeux]

Thanks for the trick! In the new version I've added conditionals inside of that logic so I'm not really sure we can do it as you mentioned.

Also, for the method lookup, I need the reference to that node, so I'd need to traverse it up anyway.

[vjeux]

• Added support for:
  • (this: any).method = this.method.bind(this);
  • const self: any = this; self.method = self.method.bind(this);
• Now removes the constructor when there's no content left but a super call.
• It bails out early if there's nothing to transform.
• Added unit tests for all those.

I'm going to run this on www now and see how it looks. All the features I want are now supported, there are probably going to be things uncovered trying it out in the real codebase.

[vjeux]

• Adding support for async functions
• Use the babylon parser to avoid issues with different line location from flow parser

[vjeux]

Fixing lint error on one of the test that prevented travis to be green :)

[keyz]

Since this has already been battle tested let's merge this? 😃