babel-traverse 6.21.0

v6.21.0

on Node.js NPM

6.21.0 (2016-12-16)

Mostly a lot of bug fixes + exposing rawMapping in babel-generator for easy source map use.

Thanks to davidaurelio, appden, and abouthiroppy for their first PRs!

🚀 New Feature

• babel-generator
  • #4979 babel-generator: Expose raw mappings. (@davidaurelio)

Exposes raw mappings when source map generation is enabled. To avoid the cost of source map generation for consumers of the raw mappings only, .map is changed to a getter that generates the source map lazily on first access.

Raw mappings can be useful for post-processing source maps more efficiently by avoiding one decoding/encoding cycle of the b64 vlq mappings. This will be used in the React Native packager.

let generator = require("babel-generator");
let generated = generator(ast, { sourceMaps: true }, sources);

// generated.rawMappings
[
  {
    name: undefined,
    generated: { line: 1, column: 0 },
    source: "inline",
    original: { line: 1, column: 0 }
  },
  ...
]

🐛 Bug Fix

• babel-generator, babel-plugin-transform-flow-comments, babel-plugin-transform-flow-strip-types
  • #4872 Print Flow optional & type annotations in function params with defaults. (@danharper)

Works with generator, transform-flow-comments, flow-strip-types.

function foo(numVal: number = 2) {}

• babel-generator, babel-plugin-transform-es2015-modules-amd, babel-plugin-transform-es2015-modules-umd
  • #4873 Ensure directives get printed in block statements. (@existentialism)

let blockStatement = t.blockStatement(
  [],
  [t.directive(t.directiveLiteral("use strict"))]
);

• babel-generator, babel-helper-builder-react-jsx, babel-plugin-transform-react-jsx, babel-types
  • #4988 Add JSXSpreadChildren but throw in JSX transform plugin. (@jridgewell)

Will still error with Spread children are not supported.

<div>{...this.props.children}</div>;

• babel-plugin-transform-es2015-block-scoping, babel-plugin-transform-react-constant-elements, babel-traverse
  • #4940 Fix React constant element bugs. (@appden)

When multiple declarators are present in a declaration, we want to insert the constant element inside the declaration rather than placing it before because it may rely on a declarator inside that same declaration.

function render() {
  const bar = "bar", renderFoo = () => <foo bar={bar} baz={baz} />, baz = "baz";

  return renderFoo();
}

When block scoped variables caused the block to be wrapped in a closure, the variable bindings remained in parent function scope, which caused the JSX element to be hoisted out of the closure.

function render(flag) {
  if (flag) {
    let bar = "bar";

    [].map(() => bar);

    return <foo bar={bar} />;
  }

  return null;
}

• babel-plugin-transform-es2015-parameters
  • #3572 Fix default parameter - rest parameter edge case. (@jridgewell)

Was erroring if the rest parameter shared the same name as a default identifier for a param, needed to be deopt'd.

const a = 1;
function rest(b = a, ...a) {
  assert.equal(b, 1);
}
rest(undefined, 2)

• babel-plugin-transform-es2015-for-of, babel-traverse
  • #5007 Bail on sharing comments with siblings if key is a string. (@existentialism)

myLabel: //woops
for (let a of b) {
  continue myLabel;
}

📝 Documentation

• Other
  • #4989 Fix links in CONTRIBUTING.md. (@abouthiroppy)
• babel-plugin-transform-runtime
  • #4991 make installing runtime/transform-runtime clearer [skip ci]. (@hzoo)
• babel-plugin-transform-es2015-unicode-regex
  • #4983 Add example to es2015-unicode-regex. (@existentialism)

🏠 Internal

• babel-helper-transform-fixture-test-runner, babel-plugin-syntax-trailing-function-commas
  • #4999 babel-helper-transform-fixture-test-runner: pass require as a global. (@hzoo)

Allows running require() in exec.js tests like for babel/babel-preset-env#95

• Other
  • #5005 internal: don't run watch with the test env (skip building with code …. (@hzoo)

Committers: 7

• Brian Ng (existentialism)
• Dan Harper (danharper)
• David Aurelio (davidaurelio)
• Henry Zhu (hzoo)
• Justin Ridgewell (jridgewell)
• Scott Kyle (appden)
• Yuta Hiroto (abouthiroppy)