c3654d83c8
* generate typescript types * improve type generator output * move generator scripts to scripts/generators * use new stringifier for generating flow types too * export summary types * add support for oneOfNodeOrValueTypes to improve type generation * export typescript types from top level, and remove module declaration * generate typescript/flow types and copy typescript types to babel-types/lib as part of make build * copy flow types to babel-types/lib as part of make build (fix #6839) * improve typing: Identifier->name should be a string, not any * avoid destructuring, to support node 4 * update doc generator to share more code, regenerate babel-types readme, pipe all generator output to stdout * regenerate babel-types readme as part of make build * improve typing: ClassProperty->key should be Identifier | StringLiteral | NumericLiteral | Expression, not any * improve typing: optional node properties are nullable, not undefinedable * improve docs: FlowClassImplements should be ClassImplements * make ts usage more friendly: when using babel-types api, make optional params | undefined, and when reading nodes keep optional params | null * rm lib/types.d.ts and lib/types.js in favor of packages/babel-types/lib * add missing variance node type, address review comments * add tests for flow variance * Comment should be a disjoint union of tagged types * update .flowconfig
@babel/generator
Turns an AST into code.
Install
npm install --save-dev @babel/generator
Usage
import {parse} from 'babylon';
import generate from '@babel/generator';
const code = 'class Example {}';
const ast = parse(code);
const output = generate(ast, { /* options */ }, code);
Options
Options for formatting output:
| name | type | default | description |
|---|---|---|---|
| auxiliaryCommentBefore | string | Optional string to add as a block comment at the start of the output file | |
| auxiliaryCommentAfter | string | Optional string to add as a block comment at the end of the output file | |
| shouldPrintComment | function | opts.comments |
Function that takes a comment (as a string) and returns true if the comment should be included in the output. By default, comments are included if opts.comments is true or if opts.minifed is false and the comment contains @preserve or @license |
| retainLines | boolean | false |
Attempt to use the same line numbers in the output code as in the source code (helps preserve stack traces) |
| retainFunctionParens | boolean | false |
Retain parens around function expressions (could be used to change engine parsing behavior) |
| comments | boolean | true |
Should comments be included in output |
| compact | boolean or 'auto' |
opts.minified |
Set to true to avoid adding whitespace for formatting |
| minified | boolean | false |
Should the output be minified |
| concise | boolean | false |
Set to true to reduce whitespace (but not as much as opts.compact) |
| filename | string | Used in warning messages | |
| jsonCompatibleStrings | boolean | false |
Set to true to run jsesc with "json": true to print "\u00A9" vs. "©"; |
Options for source maps:
| name | type | default | description |
|---|---|---|---|
| sourceMaps | boolean | false |
Enable generating source maps |
| sourceMapTarget | string | The filename of the generated code that the source map will be associated with | |
| sourceRoot | string | A root for all relative URLs in the source map | |
| sourceFileName | string | The filename for the source code (i.e. the code in the code argument). This will only be used if code is a string. |
AST from Multiple Sources
In most cases, Babel does a 1:1 transformation of input-file to output-file. However,
you may be dealing with AST constructed from multiple sources - JS files, templates, etc.
If this is the case, and you want the sourcemaps to reflect the correct sources, you'll need
to pass an object to generate as the code parameter. Keys
should be the source filenames, and values should be the source content.
Here's an example of what that might look like:
import {parse} from 'babylon';
import generate from '@babel/generator';
const a = 'var a = 1;';
const b = 'var b = 2;';
const astA = parse(a, { sourceFilename: 'a.js' });
const astB = parse(b, { sourceFilename: 'b.js' });
const ast = {
type: 'Program',
body: [].concat(astA.program.body, astB.program.body)
};
const { code, map } = generate(ast, { sourceMaps: true }, {
'a.js': a,
'b.js': b
});
// Sourcemap will point to both a.js and b.js where appropriate.