6.10.0 (2016-09-19)

We plan to include some spec compliancy bugs in patch versions. An example was the multiple default exports issue.

Spec Compliancy

• Implement ES2016 check for simple parameter list in strict mode (#106) (Timothy Gu)

It is a Syntax Error if ContainsUseStrict of FunctionBody is true and IsSimpleParameterList of FormalParameters is false. https://tc39.github.io/ecma262/2016/#sec-function-definitions-static-semantics-early-errors

More Context: tc39-notes

For example:

// this errors because it uses destructuring and default parameters
// in a function with a "use strict" directive
function a([ option1, option2 ] = []) {
  "use strict";
}

The solution would be to use a top level "use strict" or to remove the destructuring or default parameters when using a function + "use strict" or to.

New Feature

• Exact object type annotations for Flow plugin (#104) (Basil Hosmer)

Added to flow in facebook/flow@c710c40

Looks like:

var a : {| x: number, y: string |} = { x: 0, y: 'foo' };

Bug Fixes

• Include typeParameter location in ArrowFunctionExpression (#126) (Daniel Tschinder)
• Error on invalid flow type annotation with default assignment (#122) (Dan Harper)
• Fix Flow return types on arrow functions (#124) (Dan Harper)

Misc

• Add tests for export extensions (#127) (Daniel Tschinder)
• Fix Contributing guidelines [skip ci](Daniel Tschinder)