web-component-analyzer is a CLI that makes it possible to easily analyze web components. It analyzes your code and jsdoc in order to extract properties, attributes, methods, events, slots, css shadow parts and css custom properties. Works with both javascript and typescript.

Try the online playground here

➤ Why this library exists

This library was created to make it easy to document web components. It provides a simple CLI and a programmatic API to analyze your components and generate documentation in various formats. This can be useful for generating documentation for your own use, or for integrating with other tools like Storybook or VSCode.

This tool is especially useful for:

• 📖 Generating documentation for your component library
• 🔨 Integrating with other tools like Storybook or Catalog
• Δ Generating custom-elements.json for your components
• ✔️ Linting your components for missing documentation

➤ Supported Libraries

In addition to vanilla web components this tool supports web components built with the following libraries:

• lit-element
• polymer
• stencil (partial)
• lwc
• open an issue for library requests

➤ Installation

npm install -g web-component-analyzer

or

npx web-component-analyzer src

➤ Usage

wca analyze
wca analyze src --format markdown
wca analyze "src/**/*.{js,ts}" --outDir components
wca analyze my-element.js --outFile custom-elements.json
wca analyze --outFiles {dir}/custom-element.json

The analyze command analyses an optional <input glob> and emits the output to the console as default. When the <input glob> is omitted it will find all components excluding node_modules. The default format is markdown.

Options

| Option | Type | Description | | --------------------------- | -------------------------------- | ---------------------------------------------------------------------------- | | --format <format> | markdown | json | vscode | Specify output format. Default is markdown. | | --outDir <path> | directory path | Direct output to a directory where each file corresponds to a web component. | | --outFile <path> | file path | Concatenate and emit output to a single file. | | --outFiles <path> | file path with pattern | Emit output to multiple files using a pattern. Available substitutions:{dir}: The directory of the component{filename}: The filename (without ext) of the component{tagname}: The element's tag name | | --visibility <visibility> | public | protected | private | The mininmum member visibility to output. Default is public. | | --features <features> | member | method | cssproperty | csspart | event | slot | Choose specific features to output. Multiple features are given seperated by a space. All features are enabled as default.Example: --features member slot event | | --dry | boolean | Don't write any files |

➤ Output Formats

json

wca analyze src --format json --outFile custom-elements.json

Try the online playground here

This json format is for experimental and demo purposes, and is still being actively discussed. You can expect changes to this format. Please follow and contribute to the discussion at:

• https://github.com/webcomponents/custom-elements-json
• https://github.com/w3c/webcomponents/issues/776

markdown

wca analyze src --format markdown --outDir readme

Try the online playground here

Web Component Analyzer can output markdown documentation of your web components. This can either be output into a single file using --outFile or into multiple files using --outDir.

vscode

wca analyze src --format vscode --outFile vscode-html-custom-data.json

VSCode supports a JSON format called vscode custom data for the built in html editor which is set using html.customData vscode setting. Web Component Analyzer can output this format.

➤ How to integrate with other tools

VSCode

You can get rich intellisense for your custom elements in VSCode by generating a vscode-html-custom-data.json file and pointing to it in your .vscode/settings.json.

1. Generate the file

wca analyze src --format vscode --outFile vscode-html-custom-data.json

2. Point to the file in your .vscode/settings.json

{
  "html.customData": [
    "./vscode-html-custom-data.json"
  ]
}

➤ How to document your components using JSDoc

In addition to analyzing the code of your components, this library also use JSDoc to construct the documentation. It's especially a good idea to use JSDoc for documenting slots, events, css custom properties and css shadow parts as these not analyzed statically by this tool as of now (except when constructing a CustomEvent within your component).

Here's an example including all supported JSDoc tags. All JSDoc tags are on the the form @tag {type} name - comment and @tag {type} [name=default] - comment.

/**
 * Here is a description of my web component.
 * 
 * @element my-element
 * 
 * @fires change - This jsdoc tag makes it possible to document events.
 * @fires submit
 * 
 * @attr {Boolean} disabled - This jsdoc tag documents an attribute.
 * @attr {on|off} switch - Here is an attribute with either the "on" or "off" value.
 * @attr [my-attr=default value]
 * 
 * @prop {String} myProp - You can use this jsdoc tag to document properties.
 * @prop value
 * 
 * @slot - This is an unnamed slot (the default slot)
 * @slot start - This is a slot named "start".
 * @slot end
 * 
 * @cssprop --main-bg-color - This jsdoc tag can be used to document css custom properties.
 * @cssprop [--main-color=red]

 * @csspart container 
 */
class MyElement extends HTMLElement {

 /**
  * This is a description of a property with an attribute with exactly the same name: "color".
  * @type {"red"|"green"|"blue"}
  * @attr
  */
  color = "red";

  /**
   * This is a description of a property with an attribute called "my-prop".
   * @type {number}
   * @deprecated
   * @attr my-prop
   */
  myProp = 10

  static get observedAttributes () {
    return [
      /**
       * The header text of this element
       */
      "header"
    ];
  }

}

Overview of supported JSDoc tags

| JSDoc Tag | Description | | ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- | | @element | Gives your component a tag name. This JSDoc tag is useful if your 'customElements.defineis called dynamically eg. using a custom function. | |@fires | Documents events. | |@slot | Documents slots. Using an empty name here documents the unnamed (default) slot. | |@attror@attribute | Documents an attribute on your component. | |@propor@property | Documents a property on your component. | |@csspropor@cssproperty| Documents a css custom property on your component. | |@csspart` | Documents a css shadow part on your component. |

➤ Best Practices

• Use @element to specify the tag name of your component.
• Use @fires to document the events that your component fires.
• Use @slot to document the slots that your component has.
• Use @cssprop and @csspart to document the CSS custom properties and shadow parts that your component uses.
• Use @attr and @prop to document the attributes and properties of your component.
• Add a description to all your JSDoc tags.
• Use @deprecated to mark properties, methods, and events as deprecated.

➤ How does this tool analyze my components?

This tool extract information about your components by looking at your code directly and by looking at your JSDoc comments.

Code: Web Component Analyzer supports multiple libraries. Read an overview of how each library is analyzed.

JSDoc: Read next section to learn more about how JSDoc is analyzed.

➤ API

You can also directly use the underlying functionality of this tool if you don't want to use the CLI. Web Component Analyzer analyzes Typescript source files, so you will have to include the Typescript parser. Here are some examples of how to use the API.

analyzeSourceFile

import { analyzeSourceFile } from "web-component-analyzer";

const result = analyzeSourceFile(sourceFile, { checker });

analyzeSourceFile analyzes a single Typescript SourceFile and returns an AnalyzerResult.

• sourceFile: The Typescript SourceFile to analyze.
• options: An AnalyzerOptions object.
  • program: The Typescript Program object.
  • ts: The Typescript module.
  • flavors: An array of AnalyzerFlavors to use.
  • analyzeGlobalFeatures: Whether to analyze global features.
  • analyzeAllDeclarations: Whether to analyze all declarations.

analyzeText

import { analyzeText } from "web-component-analyzer";

const code = `class MyElement extends HTMLElement {

}

customElements.define("my-element", MyElement);
`;


const { results, program } = analyzeText(code);
// or
const { results, program } = analyzeText([
  { fileName: "file1.js", text: code },
  { fileName: "file2.js", text: "..." }, // these files can depend on each other
  { fileName: "file3.js", text: "...", analyze: false }
]);
// each result in "results" is the result of analyzing the corresponding text where "analyze" is not false

analyzeText analyzes a string of code or an array of virtual source files. It returns an object with the results, the Typescript program, the checker, and the analyzedSourceFiles.

• inputFiles: A string of code or an array of VirtualSourceFiles.
• config: An AnalyzerOptions object.

transformAnalyzerResult

import { transformAnalyzerResult } from "web-component-analyzer";

const result = // the result of analyzing the component using one of the above functions

const format = "markdown"; // or "json"

const output = transformAnalyzerResult(format, result, program);

// "output" is now a string containing the result of the "markdown" transformer

transformAnalyzerResult transforms an AnalyzerResult or an array of AnalyzerResults to a string.

• kind: The format to transform to. Can be markdown, json, vscode, or debug.
• results: An AnalyzerResult or an array of AnalyzerResults.
• program: The Typescript Program object.
• config: A TransformerConfig object.
  • visibility: The minimum visibility to include.
  • features: The features to include.

For more detailed examples, see EXAMPLES.md.

➤ Contributors

| | | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | | Rune Mehlsen |

➤ License

Licensed under MIT.

Maintained by Pawel Uchida-Psztyc

It looks like authors abandoned the project. While I am not planning to add new features, I will be updating dependencies.