plugin parameters "root" cannot check by "instanceof"

[chapman-cc]

the plugin return method Once first parameter "root" is not instanceof Root

I'm writing a plugin, using instanceof to check on when passing node into my functions for mutations
but even if the JSDocs indicating the type is correct, checking on debug console the prototype is correct,
it still threw an error

I know I can check node.type === "root" to get pass this but I still find not able to use instanceof weird

Example

const {Node, Root} = require("postcss");
/**
 * @type {postcss.PluginCreator<Options>}
 */
module.exports = (opts) => {
  return {
    postcssPlugin: "postcss-my-plugin",
    Once: (root) => {
      console.log(root instanceof Root); // false 
      console.log(root instanceof Node); // false 
      mutateRoot(root); // threw error
  }
}
/**
 * @type {Node} node
 */
function mutateRoot(node) {
  if (!(node instanceof Root)) {
    throw new Error("you are not passing a node");
  }
  // ... other mutations
}

[ai]

I still find not able to use instanceof weird

Unfortunately instanceof is broken in JS.

This is why we use Array.isArray() and not instanceof Array (and Error.isError() is coming).

The problem with instanceof is that node_modules could have multiple postcss versions (when we forgot to run deduplication). And they will have different Root.

(For Array/Error it happens in Web Workers and other environment where all built-in classes are different).

[Fer5050]

Gracias

[chapman-cc]

thanks @ai
that was a quick response
have a nice weekend

[codyhalfbeast-ai]

Track this from the creator