$ gnpm install rollup-pluginutils
A set of functions commonly used by Rollup plugins.
npm install --save rollup-pluginutils
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`
}
};
}
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.
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;
}
});
}
};
}
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:
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.
import { makeLegalIdentifier } from 'rollup-pluginutils';
makeLegalIdentifier( 'foo-bar' ); // 'foo_bar'
makeLegalIdentifier( 'typeof' ); // '_typeof'
Helper for treeshakable data imports
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 };
*/
Extract the names of all assignment targets from patterns.
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']
}
}
});
}
};
}
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