8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
19 lines
528 B
Markdown
19 lines
528 B
Markdown
### mapKeys
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Creates an object with keys generated by running the provided function for each key and the same values as the provided object.
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Use `Object.keys(obj)` to iterate over the object's keys.
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Use `Array.prototype.reduce()` to create a new object with the same values and mapped keys using `fn`.
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```js
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const mapKeys = (obj, fn) =>
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Object.keys(obj).reduce((acc, k) => {
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acc[fn(obj[k], k, obj)] = obj[k];
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return acc;
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}, {});
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```
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```js
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mapKeys({ a: 1, b: 2 }, (val, key) => key + val); // { a1: 1, b2: 2 }
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```
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