html-parser

Small, strict HTML‑like parser that produces a simple AST using a finite state machine.

Features

• Finite state machine parser: implemented on top of @prender-company/fsm.
• Simple AST: root, element, and text nodes with attributes.
• Strict error handling: reports line and column on parse errors.
• Node.js friendly: plain CommonJS, no runtime dependencies beyond the FSM and graceful-fs (used by the playground).

Installation

From this repository:

npm install

If you publish this package, you can then install it in another project as:

npm install html-parser

Basic usage

const HtmlParser = require('html-parser')

const source = `<div class="wrapper">
  <span>Hello</span>
</div>`

const ast = new HtmlParser(source).parse()
console.log(JSON.stringify(ast, null, 2))

parse() returns the root AST node. On invalid input, the parser logs a message like:

Parse error: Unexpected character 'x' on line 3 at column 5

and returns undefined.

AST structure

The AST is built from two node types, defined in src/types.js.

• Root and element nodes (Node):

  {
    type: 'root' | 'element',
    tagName: 'div',          // empty string for the root node
    attrs: [
      { name: 'class', value: 'wrapper' },
      // ...
    ],
    children: [ /* Node | TextNode */ ]
  }

• Text nodes (TextNode):

  {
    type: 'text',
    value: 'Hello'
  }

Attributes without an explicit value are treated as boolean and will have value: true.

Playground

There is a small playground that reads playground/index.act, parses it, and prints the resulting AST:

npm run play

Under the hood, this runs node playground/index.js, which:

• reads playground/index.act,
• parses it with HtmlParser,
• logs the AST using Node's util.inspect.

Scripts

The following npm scripts are available:

• npm start: runs node ./src/index.js (exports the parser; mainly for quick manual testing).
• npm run build: transpiles src/ into dist/ using Babel.
• npm run play: runs the playground described above.

License

MIT © Artem P