You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
82 lines
3.9 KiB
Markdown
82 lines
3.9 KiB
Markdown
5 years ago
|
# babel-generator
|
||
|
|
|
||
|
|
> Turns an AST into code.
|
||
|
|
|
||
|
|
## Install
|
||
|
|
|
||
|
|
```sh
|
||
|
|
npm install --save-dev babel-generator
|
||
|
|
```
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
|
||
|
|
```js
|
||
|
|
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`)
|
||
|
|
quotes | `'single'` or `'double'` | autodetect based on `ast.tokens` | The type of quote to use in the output
|
||
|
|
filename | string | | Used in warning messages
|
||
|
|
flowCommaSeparator | boolean | `false` | Set to `true` to use commas instead of semicolons as Flow property separators
|
||
|
|
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:
|
||
|
|
|
||
|
|
```js
|
||
|
|
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.
|
||
|
|
```
|