rollup-pluginutils

A set of functions commonly used by Rollup plugins.

Installation

1npm install --save rollup-pluginutils

Usage

addExtension

1import { addExtension } from 'rollup-pluginutils';
2
3export default function myPlugin ( options = {} ) {
4  return {
5    resolveId ( code, id ) {
6      // only adds an extension if there isn't one already
7      id = addExtension( id ); // `foo` -> `foo.js`, `foo.js -> foo.js`
8      id = addExtension( id, '.myext' ); // `foo` -> `foo.myext`, `foo.js -> `foo.js`
9    }
10  };
11}

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 or rollup-plugin-commonjs for an example of usage.

1import { attachScopes } from 'rollup-pluginutils';
2import { parse } from 'acorn';
3import { walk } from 'estree-walker';
4
5export default function myPlugin ( options = {} ) {
6  return {
7    transform ( code ) {
8      const ast = parse( ast, {
9        ecmaVersion: 6,
10        sourceType: 'module'
11      });
12
13      let scope = attachScopes( ast, 'scope' );
14
15      walk( ast, {
16        enter ( node ) {
17          if ( node.scope ) scope = node.scope;
18
19          if ( !scope.contains( 'foo' ) ) {
20            // `foo` is not defined, so if we encounter it,
21            // we assume it's a global
22          }
23        },
24        leave ( node ) {
25          if ( node.scope ) scope = scope.parent;
26        }
27      });
28    }
29  };
30}

createFilter

1import { createFilter } from 'rollup-pluginutils';
2
3export default function myPlugin ( options = {} ) {
4  // `options.include` and `options.exclude` can each be a minimatch
5  // pattern, or an array of minimatch patterns, relative to process.cwd()
6  var filter = createFilter( options.include, options.exclude );
7
8  return {
9    transform ( code, id ) {
10      // if `options.include` is omitted or has zero length, filter
11      // will return `true` by default. Otherwise, an ID must match
12      // one or more of the minimatch patterns, and must not match
13      // any of the `options.exclude` patterns.
14      if ( !filter( id ) ) return;
15
16      // proceed with the transformation...
17    }
18  };
19}

makeLegalIdentifier

1import { makeLegalIdentifier } from 'rollup-pluginutils';
2
3makeLegalIdentifier( 'foo-bar' ); // 'foo_bar'
4makeLegalIdentifier( 'typeof' ); // '_typeof'

dataToEsm

Helper for treeshakable data imports

1import { dataToEsm } from 'rollup-pluginutils';
2
3const esModuleSource = dataToEsm({
4  custom: 'data',
5  to: ['treeshake']
6}, options = {
7  compact: false,
8  indent: '\t',
9  preferConst: false,
10  objectShorthand: false,
11  namedExports: true
12});
13/*
14Outputs the string ES module source:
15  export const custom = 'data';
16  export const to = ['treeshake'];
17  export default { custom, to };
18*/

License

MIT