44 lines
1.1 KiB
Markdown
44 lines
1.1 KiB
Markdown
---
|
|
title: Check if object has key
|
|
tags: object
|
|
author: chalarangelo
|
|
cover: cloudy-mountaintop
|
|
firstSeen: 2019-10-15T15:45:13+03:00
|
|
lastUpdated: 2020-10-19T22:49:51+03:00
|
|
---
|
|
|
|
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.
|
|
|
|
```js
|
|
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;
|
|
})
|
|
);
|
|
};
|
|
```
|
|
|
|
```js
|
|
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
|
|
```
|