30秒学会 JavaScript 片段 – hasKey

Returns true if the target value exists in a JSON object, false otherwise.

Check if keys is non-empty and use Array.prototype.every() to sequentially check its keys to internal depth of the object, obj.
Use Object.prototype.hasOwnProperty() to check if obj does not have the current key or is not an object, stop propagation and return false.
Otherwise assign the key’s value to obj to use on the next iteration.
Return false beforehand if given key list is empty.

代码片段

const hasKey = (obj, keys) => {
  return (
    keys.length > 0 &&
    keys.every(key => {
      if (typeof obj !== 'object' || !obj.hasOwnProperty(key)) return false;
      obj = obj[key];
      return true;
    })
  );
};

使用样例

let obj = {
  a: 1,
  b: { c: 4 },
  'b.d': 5
};
hasKey(obj, ['a']); // true
hasKey(obj, ['b']); // true
hasKey(obj, ['b', 'c']); // true
hasKey(obj, ['b.d']); // true
hasKey(obj, ['d']); // false
hasKey(obj, ['c']); // false
hasKey(obj, ['b', 'f']); // false