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# rollup-pluginutils
A set of functions commonly used by Rollup plugins.
## Installation
```bash
npm install --save rollup-pluginutils
```
## Usage
### addExtension
```js
import { addExtension } from 'rollup-pluginutils';
export default function myPlugin ( options = {} ) {
return {
resolveId ( code, id ) {
// only adds an extension if there isn't one already
id = addExtension( id ); // `foo` -> `foo.js`, `foo.js -> foo.js`
id = addExtension( id, '.myext' ); // `foo` -> `foo.myext`, `foo.js -> `foo.js`
}
};
}
```
### attachScopes
This function attaches `Scope` objects to the relevant nodes of an AST. Each `Scope` object has a `scope.contains(name)` method that returns `true` if a given name is defined in the current scope or a parent scope.
See [rollup-plugin-inject](https://github.com/rollup/rollup-plugin-inject) or [rollup-plugin-commonjs](https://github.com/rollup/rollup-plugin-commonjs) for an example of usage.
```js
import { attachScopes } from 'rollup-pluginutils';
import { walk } from 'estree-walker';
export default function myPlugin ( options = {} ) {
return {
transform ( code ) {
const ast = this.parse( code );
let scope = attachScopes( ast, 'scope' );
walk( ast, {
enter ( node ) {
if ( node.scope ) scope = node.scope;
if ( !scope.contains( 'foo' ) ) {
// `foo` is not defined, so if we encounter it,
// we assume it's a global
}
},
leave ( node ) {
if ( node.scope ) scope = scope.parent;
}
});
}
};
}
```
### createFilter
```js
import { createFilter } from 'rollup-pluginutils';
export default function myPlugin ( options = {} ) {
// `options.include` and `options.exclude` can each be a minimatch
// pattern, or an array of minimatch patterns, relative to process.cwd()
var filter = createFilter( options.include, options.exclude );
return {
transform ( code, id ) {
// if `options.include` is omitted or has zero length, filter
// will return `true` by default. Otherwise, an ID must match
// one or more of the minimatch patterns, and must not match
// any of the `options.exclude` patterns.
if ( !filter( id ) ) return;
// proceed with the transformation...
}
};
}
```
If you want to resolve the patterns against a directory other than
`process.cwd()`, you can additionally pass a `resolve` option:
```js
var filter = createFilter( options.include, options.exclude, {resolve: '/my/base/dir'} )
```
If `resolve` is a string, then this value will be used as the base directory.
Relative paths will be resolved against `process.cwd()` first. If `resolve` is
`false`, then the patterns will not be resolved against any directory. This can
be useful if you want to create a filter for virtual module names.
### makeLegalIdentifier
```js
import { makeLegalIdentifier } from 'rollup-pluginutils';
makeLegalIdentifier( 'foo-bar' ); // 'foo_bar'
makeLegalIdentifier( 'typeof' ); // '_typeof'
```
### dataToEsm
Helper for treeshakable data imports
```js
import { dataToEsm } from 'rollup-pluginutils';
const esModuleSource = dataToEsm({
custom: 'data',
to: ['treeshake']
}, {
compact: false,
indent: '\t',
preferConst: false,
objectShorthand: false,
namedExports: true
});
/*
Outputs the string ES module source:
export const custom = 'data';
export const to = ['treeshake'];
export default { custom, to };
*/
```
### extractAssignedNames
Extract the names of all assignment targets from patterns.
```js
import { extractAssignedNames } from 'rollup-pluginutils';
import { walk } from 'estree-walker';
export default function myPlugin ( options = {} ) {
return {
transform ( code ) {
const ast = this.parse( code );
walk( ast, {
enter ( node ) {
if ( node.type === 'VariableDeclarator' ) {
const declaredNames = extractAssignedNames(node.id);
// do something with the declared names
// e.g. for `const {x, y: z} = ... => declaredNames = ['x', 'z']
}
}
});
}
};
}
```
## License
MIT
|
