patoi/ultima-thule

Testing VS Code and JavaScript + JSDoc type checking

ultima-thule

It's a sandbox project to testing VS Code and JavaScript + JSDoc type checking.

Read more: https://medium.com/@trukrs/type-safe-javascript-with-jsdoc-7a2a63209b76

YOU MUST ENABLE VALIDATION IN VS CODE PREFERENCES

javascript.validate.enable=true

( Related issue: microsoft/vscode#39305 )

Optionally, you can turn on checking feature to all files:

"javascript.implicitProjectConfig.checkJs": true

JSDoc support in VS Code:

• https://github.com/Microsoft/TypeScript/wiki/JsDoc-support-in-JavaScript
• https://github.com/Microsoft/TypeScript/wiki/JavaScript-Language-Service-in-Visual-Studio#JsDoc

Validation example

When you edit your code, the VS Code checking JavaScript files automatically based on JSDoc.

Age must be a number.

// Wrong type!
const jane = new Person({
    name: 'Jane Doe',
    age: '10',
})

VS Code shows a message about this error:

1. line: (property) age?: number - means it is optional and number
2. line: optional, must be between 0-150, default is 0 - textual documentation
3. line: Type 'string' is not assignable to type 'number'.ts(2322) - error message
4. line: person.js(6, 8): The expected type comes from property 'age' which is declared here on type '{ name: string; age?: number; }' – detailed error description: you can click on person.js for more information