59 lines
1.2 KiB
Markdown
59 lines
1.2 KiB
Markdown
---
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title: Deep map object keys
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tags: object,recursion
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cover: duck-plants
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firstSeen: 2018-11-29T15:22:53+02:00
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lastUpdated: 2020-09-15T16:28:04+03:00
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---
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Deep maps an object's keys.
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- Creates an object with the same values as the provided object and keys generated by running the provided function for each key.
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- Use `Object.keys()` 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 deepMapKeys = (obj, fn) =>
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Array.isArray(obj)
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? obj.map(val => deepMapKeys(val, fn))
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: typeof obj === 'object'
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? Object.keys(obj).reduce((acc, current) => {
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const key = fn(current);
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const val = obj[current];
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acc[key] =
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val !== null && typeof val === 'object' ? deepMapKeys(val, fn) : val;
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return acc;
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}, {})
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: obj;
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```
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```js
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const obj = {
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foo: '1',
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nested: {
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child: {
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withArray: [
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{
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grandChild: ['hello']
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}
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]
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}
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}
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};
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const upperKeysObj = deepMapKeys(obj, key => key.toUpperCase());
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/*
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{
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"FOO":"1",
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"NESTED":{
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"CHILD":{
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"WITHARRAY":[
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{
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"GRANDCHILD":[ 'hello' ]
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}
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]
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}
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}
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}
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*/
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```
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