Create a deep freeze function for object as constant

April 20, 2017

In Javascipt, constants are not really “constants”. When you import some kinds of array from a file, and then alter it, you can actually change the “constant”. To avoid this, simply calling the following deepFreeze() to the array or the object, and it will throw an error for mis-use.

export default function deepFreeze(stuff) {
  Object.freeze(stuff);

  Reflect.ownKeys(stuff).forEach(key => {
    let prop = stuff[key];

    if (
      prop !== null &&
      (typeof prop === 'object' || typeof prop === 'function' || Array.isArray(prop)) &&
      !Object.isFrozen(prop)
    ) {
      deepFreeze(prop);
    }
  });
}