35 lines
983 B
Markdown
35 lines
983 B
Markdown
---
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title: hasKey
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tags: object,recursion,intermediate
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---
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Returns `true` if the target value exists in a JSON object, `false` otherwise.
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Check if the key contains `.`, use `String.prototype.split('.')[0]` to get the first part and store as `_key`.
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Use `typeof` to check if the contents of `obj[key]` are an `object` and, if so, call `hasKey` with that object and the remainder of the `key`.
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Otherwise, use `Object.keys(obj)` in combination with `Array.prototype.includes()` to check if the given `key` exists.
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```js
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const hasKey = (obj, key) => {
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if (key.includes('.')) {
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let _key = key.split('.')[0];
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if (typeof obj[_key] === 'object') return hasKey(obj[_key], key.slice(key.indexOf('.') + 1));
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}
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return Object.keys(obj).includes(key);
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};
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```
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```js
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let obj = {
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a: 1,
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b: { c: 4 },
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'd.e': 5
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};
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hasKey(obj, 'a'); // true
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hasKey(obj, 'b'); // true
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hasKey(obj, 'b.c'); // true
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hasKey(obj, 'd.e'); // true
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hasKey(obj, 'd'); // false
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hasKey(obj, 'f'); // false
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```
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