babel-generator
Turns an AST into code.
Install
npm install --save-dev babel-generatorUsage
;; const code = 'class Example {}';const ast = ; const output = ;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:
;; const a = 'var a = 1;';const b = 'var b = 2;';const astA = ;const astB = ;const ast = type: 'Program' body: ; const code map = ; // Sourcemap will point to both a.js and b.js where appropriate.