Check if object has key

JavaScript, Object · Oct 19, 2020

Checks if the target value exists in a JSON object.

  • 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.
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;
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

Written by Angelos Chalaris

I'm Angelos Chalaris, a JavaScript software engineer, based in Athens, Greece. The best snippets from my coding adventures are published here to help others learn to code.

If you want to keep in touch, follow me on GitHub.

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