***ESTree*** compatibility as plugin ([#277](https://github.com/babel/babylon/pull/277)) (Daniel Tschinder)
We finally introduce a new compatibility layer for ESTree. To put babylon into ESTree-compatible mode the new plugin `estree` can be enabled. In this mode the parser will output an AST that is compliant to the specs of [ESTree](https://github.com/estree/estree/)
We highly recommend everyone who uses babylon outside of babel to use this plugin. This will make it much easier for users to switch between different ESTree-compatible parsers. We so far tested several projects with different parsers and exchanged their parser to babylon and in nearly all cases it worked out of the box. Some other estree-compatible parsers include `acorn`, `esprima`, `espree`, `flow-parser`, etc.
To enable `estree` mode simply add the plugin in the config:
```json
{
"plugins": [ "estree" ]
}
```
If you want to migrate your project from non-ESTree mode to ESTree, have a look at our [Readme](https://github.com/babel/babylon/#output), where all deviations are mentioned.
Add a parseExpression public method ([#213](https://github.com/babel/babylon/pull/213)) (jeromew)
Babylon exports a new function to parse a single expression
```js
import { parseExpression } from 'babylon';
const ast = parseExpression('x || y && z', options);
```
The returned AST will only consist of the expression. The options are the same as for `parse()`
A new option was added to babylon allowing to change the intial linenumber for the first line which is usually `1`.
Changing this for example to `100` will make line `1` of the input source to be marked as line `100`, line `2` as `101`, line `3` as `102`, ...
Function predicate declaration ([#103](https://github.com/babel/babylon/pull/103)) (Panagiotis Vekris)
Added support for function predicates which flow introduced in version 0.33.0
```js
declare function is_number(x: mixed): boolean %checks(typeof x === "number");
```
Allow imports in declare module ([#315](https://github.com/babel/babylon/pull/315)) (Daniel Tschinder)
Added support for imports within module declarations which flow introduced in version 0.37.0
```js
declare module "C" {
import type { DT } from "D";
declare export type CT = { D: DT };
}
```
### :eyeglasses: Spec Compliancy
Forbid semicolons after decorators in classes ([#352](https://github.com/babel/babylon/pull/352)) (Kevin Gibbons)
This example now correctly throws an error when there is a semicolon after the decorator:
```js
class A {
@a;
foo(){}
}
```
Keywords are not allowed as local specifier ([#307](https://github.com/babel/babylon/pull/307)) (Daniel Tschinder)
Using keywords in imports is not allowed anymore:
```js
import { default } from "foo";
import { a as debugger } from "foo";
```
Do not allow overwritting of primitive types ([#314](https://github.com/babel/babylon/pull/314)) (Daniel Tschinder)
In flow it is now forbidden to overwrite the primitve types `"any"`, `"mixed"`, `"empty"`, `"bool"`, `"boolean"`, `"number"`, `"string"`, `"void"` and `"null"` with your own type declaration.
Disallow import type { type a } from … ([#305](https://github.com/babel/babylon/pull/305)) (Daniel Tschinder)
The following code now correctly throws an error
```js
import type { type a } from "foo";
```
Don't parse class properties without initializers when classProperties is disabled and Flow is enabled ([#300](https://github.com/babel/babylon/pull/300)) (Andrew Levine)
Ensure that you enable the `classProperties` plugin in order to enable correct parsing of class properties. Prior to this version it was possible to parse them by enabling the `flow` plugin but this was not intended the behaviour.
If you enable the flow plugin you can only define the type of the class properties, but not initialize them.
Fix export default async function to be FunctionDeclaration ([#324](https://github.com/babel/babylon/pull/324)) (Daniel Tschinder)
Parsing the following code now returns a `FunctionDeclaration` AST node instead of `FunctionExpression`.
```js
export default async function bar() {};
```
### :nail_care: Polish
Improve error message on attempt to destructure named import ([#288](https://github.com/babel/babylon/pull/288)) (Brian Ng)
### :bug: Bug Fix
Fix negative number literal typeannotations ([#366](https://github.com/babel/babylon/pull/366)) (Daniel Tschinder)
Ensure takeDecorators is called on exported class ([#358](https://github.com/babel/babylon/pull/358)) (Brian Ng)
ESTree: correctly change literals in all cases ([#368](https://github.com/babel/babylon/pull/368)) (Daniel Tschinder)
Correctly convert RestProperty to Assignable ([#339](https://github.com/babel/babylon/pull/339)) (Daniel Tschinder)
Fix #321 by allowing question marks in type params ([#338](https://github.com/babel/babylon/pull/338)) (Daniel Tschinder)
Fix #336 by correctly setting arrow-param ([#337](https://github.com/babel/babylon/pull/337)) (Daniel Tschinder)
Fix parse error when destructuring `set` with default value ([#317](https://github.com/babel/babylon/pull/317)) (Brian Ng)
Before y and z would just be the same value anyway so there is no reason to need to have both.
**SyntaxError**: A trailing comma is not permitted after the rest element (1:16)
```js
let { x, y, ...z, } = obj;
```
The rationale for this is that the use case for trailing comma is that you can add something at the end without affecting the line above. Since a RestProperty always has to be the last property it doesn't make sense.
---
get / set are valid property names in default assignment (#142) ([@jezell](https://github.com/jezell))
```js
// valid
function something({ set = null, get = null }) {}
```
## v6.11.2 (2016-09-23)
### Bug Fix
- [#139](https://github.com/babel/babylon/issues/139) Don't do the duplicate check if not an identifier (#140) @hzoo
```js
// regression with duplicate export check
SyntaxError: ./typography.js: `undefined` has already been exported. Exported identifiers must be unique. (22:13)
Bail out for now, and make a change to account for destructuring in the next release.
## 6.11.1 (2016-09-22)
### Bug Fix
- [#137](https://github.com/babel/babylon/pull/137) - Fix a regression with duplicate exports - it was erroring on all keys in `Object.prototype`. @danez
```javascript
export toString from './toString';
```
```bash
`toString` has already been exported. Exported identifiers must be unique. (1:7)
> 1 | export toString from './toString';
| ^
2 |
```
## 6.11.0 (2016-09-22)
### Spec Compliancy (will break CI)
- Disallow duplicate named exports ([#107](https://github.com/babel/babylon/pull/107)) @kaicataldo
```js
// Only one default export allowed per module. (2:9)
export default function() {};
export { foo as default };
// Only one default export allowed per module. (2:0)
export default {};
export default function() {};
// `Foo` has already been exported. Exported identifiers must be unique. (2:0)
export { Foo };
export class Foo {};
```
### New Feature (Syntax)
- Add support for computed class property names ([#121](https://github.com/babel/babylon/pull/121)) @motiz88
```js
// AST
interface ClassProperty <:Node{
type: "ClassProperty";
key: Identifier;
value: Expression;
computed: boolean; // added
}
```
```js
// with "plugins": ["classProperties"]
class Foo {
[x]
['y']
}
class Bar {
[p]
[m] () {}
}
```
### Bug Fix
- Fix `static` property falling through in the declare class Flow AST ([#135](https://github.com/babel/babylon/pull/135)) @danharper
```js
declare class X {
a: number;
static b: number; // static
c: number; // this was being marked as static in the AST as well
}
```
### Polish
- Rephrase "assigning/binding to rvalue" errors to include context ([#119](https://github.com/babel/babylon/pull/119)) @motiz88
```js
// Used to error with:
// SyntaxError: Assigning to rvalue (1:0)
// Now:
// Invalid left-hand side in assignment expression (1:0)
3 = 4
// Invalid left-hand side in for-in statement (1:5)
for (+i in {});
```
### Internal
- Fix call to `this.parseMaybeAssign` with correct arguments ([#133](https://github.com/babel/babylon/pull/133)) @danez
- Add semver note to changelog ([#131](https://github.com/babel/babylon/pull/131)) @hzoo
## 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](https://github.com/babel/babylon/pull/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](https://github.com/rwaldron/tc39-notes/blob/master/es7/2015-07/july-29.md#611-the-scope-of-use-strict-with-respect-to-destructuring-in-parameter-lists)
For example:
```js
// 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](https://github.com/babel/babylon/pull/104)) (Basil Hosmer)
Added to flow in https://github.com/facebook/flow/commit/c710c40aa2a115435098d6c0dfeaadb023cd39b8
Looks like:
```js
var a : {| x: number, y: string |} = { x: 0, y: 'foo' };
```
### Bug Fixes
* Include `typeParameter` location in `ArrowFunctionExpression` ([#126](https://github.com/babel/babylon/pull/126)) (Daniel Tschinder)
* Error on invalid flow type annotation with default assignment ([#122](https://github.com/babel/babylon/pull/122)) (Dan Harper)
The only change is to remove the `babel-runtime` dependency by compiling with Babel's ES2015 loose mode. So using babylon standalone should be smaller.
## 6.9.1 (2016-08-23)
This release contains mainly small bugfixes but also updates babylons default mode to es2017. The features for `exponentiationOperator`, `asyncFunctions` and `trailingFunctionCommas` which previously needed to be activated via plugin are now enabled by default and the plugins are now no-ops.
### Bug Fixes
- Fix issues with default object params in async functions ([#96](https://github.com/babel/babylon/pull/96)) @danez
- Fix issues with flow-types and async function ([#95](https://github.com/babel/babylon/pull/95)) @danez
- Fix arrow functions with destructuring, types & default value ([#94](https://github.com/babel/babylon/pull/94)) @danharper
- Fix declare class with qualified type identifier ([#97](https://github.com/babel/babylon/pull/97)) @danez
- Remove exponentiationOperator, asyncFunctions, trailingFunctionCommas plugins and enable them by default ([#98](https://github.com/babel/babylon/pull/98)) @danez
## 6.9.0 (2016-08-16)
### New syntax support
- Add JSX spread children ([#42](https://github.com/babel/babylon/pull/42)) @calebmer
(Be aware that React is not going to support this syntax)
- Add support for declare module.exports ([#72](https://github.com/babel/babylon/pull/72)) @danez
```js
declare module "foo" {
declare module.exports: {}
}
```
### New Features
- If supplied, attach filename property to comment node loc. ([#80](https://github.com/babel/babylon/pull/80)) @divmain
- Add identifier name to node loc field ([#90](https://github.com/babel/babylon/pull/90)) @kittens
### Bug Fixes
- Fix exponential operator to behave according to spec ([#75](https://github.com/babel/babylon/pull/75)) @danez
- Fix lookahead to not add comments to arrays which are not cloned ([#76](https://github.com/babel/babylon/pull/76)) @danez
- Fix accidental fall-through in Flow type parsing. ([#82](https://github.com/babel/babylon/pull/82)) @xiemaisi
- Only allow declares inside declare module ([#73](https://github.com/babel/babylon/pull/73)) @danez
- Small fix for parsing type parameter declarations ([#83](https://github.com/babel/babylon/pull/83)) @gabelevi
- Fix arrow param locations with flow types ([#57](https://github.com/babel/babylon/pull/57)) @danez
- Fixes SyntaxError position with flow optional type ([#65](https://github.com/babel/babylon/pull/65)) @danez
### Internal
- Add codecoverage to tests @danez
- Fix tests to not save expected output if we expect the test to fail @danez
- Make a shallow clone of babel for testing @danez
- chore(package): update cross-env to version 2.0.0 ([#77](https://github.com/babel/babylon/pull/77)) @greenkeeperio-bot
- chore(package): update ava to version 0.16.0 ([#86](https://github.com/babel/babylon/pull/86)) @greenkeeperio-bot
- chore(package): update babel-plugin-istanbul to version 2.0.0 ([#89](https://github.com/babel/babylon/pull/89)) @greenkeeperio-bot
- chore(package): update nyc to version 8.0.0 ([#88](https://github.com/babel/babylon/pull/88)) @greenkeeperio-bot
## 6.8.4 (2016-07-06)
### Bug Fixes
- Fix the location of params, when flow and default value used ([#68](https://github.com/babel/babylon/pull/68)) @danez
## 6.8.3 (2016-07-02)
### Bug Fixes
- Fix performance regression introduced in 6.8.2 with conditionals ([#63](https://github.com/babel/babylon/pull/63)) @danez
## 6.8.2 (2016-06-24)
### Bug Fixes
- Fix parse error with yielding jsx elements in generators `function* it() { yield <a></a>; }` ([#31](https://github.com/babel/babylon/pull/31)) @eldereal
- When cloning nodes do not clone its comments ([#24](https://github.com/babel/babylon/pull/24)) @danez
- Fix parse errors when using arrow functions with an spread element and return type `(...props): void => {}` ([#10](https://github.com/babel/babylon/pull/10)) @danez
- Fix leading comments added from previous node ([#23](https://github.com/babel/babylon/pull/23)) @danez
- Remove line terminator restriction after await keyword @kittens
- Remove grouped type arrow restriction as it seems flow no longer has it @kittens
- Fix parse error with generic methods that have the name `get` or `set``class foo { get() {} }` ([#55](https://github.com/babel/babylon/pull/55)) @vkurchatkin
- Fix parse error with arrow functions that have flow type parameter declarations `<T>(x: T): T => x;` ([#54](https://github.com/babel/babylon/pull/54)) @gabelevi
### Documentation
- Document AST differences from ESTree ([#41](https://github.com/babel/babylon/pull/41)) @nene
- Move ast spec from babel/babel ([#46](https://github.com/babel/babylon/pull/46)) @hzoo
There is also a new node type, `ForAwaitStatement`.
> [Async generators and for-await](https://github.com/tc39/proposal-async-iteration) are now a [stage 2 proposal](https://github.com/tc39/ecma262#current-proposals).
