Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/pugjs/babel-plugin-transform-with
Babel plugin to convert "with" statements into strict mode-compatible JavaScript.
https://github.com/pugjs/babel-plugin-transform-with
Last synced: 4 months ago
JSON representation
Babel plugin to convert "with" statements into strict mode-compatible JavaScript.
- Host: GitHub
- URL: https://github.com/pugjs/babel-plugin-transform-with
- Owner: pugjs
- License: mit
- Created: 2016-09-03T04:07:39.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2016-10-01T16:19:49.000Z (over 8 years ago)
- Last Synced: 2024-10-01T06:31:34.541Z (4 months ago)
- Language: JavaScript
- Size: 27.3 KB
- Stars: 7
- Watchers: 5
- Forks: 2
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- Changelog: HISTORY.md
- License: LICENSE.md
Awesome Lists containing this project
README
# babel-plugin-transform-with
Babel plugin that turns `with` statements into strict-mode JS.
- [x] Alternative strict-mode-compatible syntax
- [x] Falls back to global variables if a variable is not available in the object
- [x] Supports [`this` references][this]
- [x] Supports [nesting]
- [x] Supports [`return`], [`break`], [`continue`]
- [x] Supports [`yield`], [`await`]
- [ ] Supports `arguments` (unlikely to be supported)
[](https://travis-ci.org/pugjs/babel-plugin-transform-with)
[](https://david-dm.org/pugjs/babel-plugin-transform-with)
[](https://www.npmjs.org/package/babel-plugin-transform-with)
[this]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/this
[nesting]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/nested
[`return`]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/return
[`break`]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/loop-outside-single
[`continue`]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/loop-outside-multiple
[`yield`]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/generator-function
[`await`]: https://github.com/pugjs/babel-plugin-transform-with/tree/master/test/fixtures/with/async-function
## Alternative syntax
Babel errors out on any `with` statements during parsing by default, which can be frustrating when eventually the code will be converted anyway. This plugin implements an escape hatch using comments:
```js
with (obj || {}) {
console.log(str);
}
// The `with` block above is equivalent to the following:
// @with
{
obj || {};
console.log(str);
}
```
This feature is enabled by default, but you could set `alternative` option to `false` to disable it.
## Example output
```js
with (obj || {}) {
console.log(str);
}
```
```js
var _ref = obj || {};
(function (console, str) {
console.log(str);
})("console" in _ref ?
_ref.console :
typeof console !== "undefined" ?
console :
undefined,
"str" in _ref ?
_ref.str :
typeof str !== "undefined" ?
a :
undefined);
```
## Exclude variables
If there are certain variables that should be regarded as globals and excluded from the closure, there are two ways to make this possible.
The plugin accepts an `exclude` option that takes an array of excluded variable names. This option applies to all `with`s compiled, so it is usually more suitable to be used when the variable is a global, like `Array`, `Object`, `process`, or `console`.
If you want to tweak the excluded variables on a per-instance basis, you can use `@with ignore` annotation (which works for both `with () {}` construct and the alternative syntax):
```js
var i = 0, j = 0, k = 0;
var obj = { i: 1, j: 1, k: 0 };
// @with exclude: i
with (obj) {
console.log(i, j);
}
// @with exclude: i, j
with (obj) {
console.log(i, j);
}
```
results in
```js
var i = 0, j = 0, k = 0;
var obj = { i: 1, j: 1, k: 0 };
(function (console, j) {
console.log(i, j);
})("console" in obj ? obj.console : typeof console !== "undefined" ? console : undefined, "j" in obj ? obj.j : typeof j !== "undefined" ? j : undefined);
(function (console) {
console.log(i, j);
})("console" in obj ? obj.console : typeof console !== "undefined" ? console : undefined);
```