Keep track of what is polyfilled

[shgysk8zer0]

Some features cannot be fully implemented, and it would be helpful to have a consistent way of telling.

I'm thinking something along the lines of the following:

  export const key = Symbol.for('_polyfilled');

  export function markPolyfilled(thing, name) {
    if (thing.hasOwnProperty(key)) {
      thing[key].push(name);
    } else {
      Object.defineProperty(thing, key, {
        value: [name],
        enumerable: false,
        configurable: false,
        writable: false,
      });
    }    
  }

  export function isPolyfilled(thing, name) {
    return thing.hasOwnProperty(key) && thing[key].includes(name);
  }

Using Symbol.for() makes it easily accessible in other scripts/modules without importing.

Using Object.defineProperty() with enumerable set to false makes it so Object.keys() and Object.entries() won't list this.

Having an array allows for multiple records of polyfills on the same thing without conflict.

Example

  const obj = { num: 42 };
  markPolyfilled(obj, 'foo');
  markPolyfilled(obj, 'bar');
  console.log({
    foo: isPolyfilled(obj, 'foo'),
    bar: isPolyfilled(obj, 'bar'),
    bazz: isPolyfilled(obj, 'bazz'),
    keys: Object.keys(obj),
    symbols: Object.getOwnPropertySymbols(obj),
  });

[shgysk8zer0]

I've added the markPolyfilled() to utils.js and handle it automatically in polyfillMethod(), polyfillGetterSetter(), and overwriteMethod().

Making this widely supported is largely a matter of re-writing a ton of polyfills that are more direct. Will take some effort to do so.