Function hashJSObj

src/Hash.ts:136–209

(obj: object | Function)

// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
function hashJSObj(obj: object | Function): number {
  let hashed: number | undefined;
  if (usingWeakMap) {
    // @ts-expect-error weakMap is defined
    hashed = weakMap.get(obj);
    if (hashed !== undefined) {
      return hashed;
    }
  }

  // @ts-expect-error used for old code, will be removed
  hashed = obj[UID_HASH_KEY];
  if (hashed !== undefined) {
    return hashed;
  }

  if (!canDefineProperty) {
    // @ts-expect-error used for old code, will be removed
    hashed = obj.propertyIsEnumerable && obj.propertyIsEnumerable[UID_HASH_KEY];
    if (hashed !== undefined) {
      return hashed;
    }

    hashed = getIENodeHash(obj);
    if (hashed !== undefined) {
      return hashed;
    }
  }

  hashed = nextHash();

  if (usingWeakMap) {
    // @ts-expect-error weakMap is defined
    weakMap.set(obj, hashed);
  } else if (isExtensible !== undefined && isExtensible(obj) === false) {
    throw new Error('Non-extensible objects are not allowed as keys.');
  } else if (canDefineProperty) {
    Object.defineProperty(obj, UID_HASH_KEY, {
      enumerable: false,
      configurable: false,
      writable: false,
      value: hashed,
    });
  } else if (
    obj.propertyIsEnumerable !== undefined &&
    obj.propertyIsEnumerable === obj.constructor.prototype.propertyIsEnumerable
  ) {
    // Since we can't define a non-enumerable property on the object
    // we'll hijack one of the less-used non-enumerable properties to
    // save our hash on it. Since this is a function it will not show up in
    // `JSON.stringify` which is what we want.
    obj.propertyIsEnumerable = function () {
      return this.constructor.prototype.propertyIsEnumerable.apply(
        this,
        // eslint-disable-next-line prefer-rest-params
        arguments
      );
    };