ranlexer

Tiny JavaScript ast parser and generator

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Install

Using npm:

npm install ranlexer --save

Library Progress

This library is still under active development. Most common code manipulation/generation use cases are implemented, but there's still a lot of work to do. Please open an issue if you find a feature missing, bug, or question that isn't in the issue.

Usage

ranlexer can export the following methods

• parse: Parse the code into an ast
• walk: Walk through the structure of the ast to perform custom operations
• generate: Parse the ast into code
• build: A lightweight build tool that supports treeshaking

parse

Parse the code into an ast:

import { parse } from 'ranlexer';

const code = 'let a = 1;';
const ast = parse(code);

walk

Walk through the structure of the ast to perform custom operations

There are two options：

• ast: ast structure node
• opts: One object with two methods in it

// Export the type of the ast node
import type { Types } from 'ranlexer'

const opts = {
  enter: (node: Types.Node) => {
    // Enter the processing of the node
  },
  leave: (node: Types.Node) => {
    // Leave the node processing
  }
walk(ast, opts)

generate

Parse the ast into code:

import { generate } from 'ranlexer';

const ast = {
  type: NodeType.Program,
  start: 0,
  end: 9,
  body: [
    {
      type: NodeType.VariableDeclaration,
      start: 0,
      end: 9,
      declarations: [
        {
          type: NodeType.VariableDeclarator,
          id: {
            type: NodeType.Identifier,
            name: 'a',
            start: 4,
            end: 5,
          },
          start: 4,
          end: 9,
          init: {
            type: NodeType.Literal,
            value: '1',
            raw: '1',
            start: 8,
            end: 9,
          },
        },
      ],
      kind: 'let',
    },
  ],
};
const code = generate(ast); // 'let a = 1;'

build

A lightweight build tool that supports treeshaking

import { build } from 'ranlexer';

const bundle = await build(option);

Generate a bundle by passing in options，All options are well, optional:

• input: Build entry, if not set, the default value is ./index.js
• output: Path to the build output file. If not set, the default value is ./dist/index.js
• external: String array，the modules in the array are not built

The bundle has two methods:

• generate: generate is to output the built code directly,

import { build } from 'ranlexer';

const bundle = await build(option);

const code = bundle.generate();

• write: write is to output the file to a directory.

import { build } from 'ranlexer';

const bundle = await build(option);

bundle.write();

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LICENSE (MIT)