Deep freezes an object.

Use Object.keys() to get all the properties of the passed object, Array.prototype.forEach() to iterate over them.
Call Object.freeze(obj) recursively on all properties, checking if each one is frozen using Object.isFrozen() and applying deepFreeze() as necessary.
Finally, use Object.freeze() to freeze the given object.

代码片段

const deepFreeze = obj => {
  Object.keys(obj).forEach(prop => {
    if (obj[prop] === 'object' && !Object.isFrozen(obj[prop])) deepFreeze(v[prop]);
  });
  return Object.freeze(obj);
};

使用样例

'use strict';

const o = deepFreeze([1, [2, 3]]);

o[0] = 3; // not allowed
o[1][0] = 4; // not allowed as well