28 lines
1.1 KiB
Markdown
28 lines
1.1 KiB
Markdown
---
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title: unflattenObject
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tags: object,advanced
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---
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Unflatten an object with the paths for keys.
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- Use nested `Array.prototype.reduce()` to convert the flat path to a leaf node.
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- Split each key with a dot delimiter (`.`) using `Array.prototype.split('.')`and use `Array.prototype.reduce()` to add or objects against the keys.
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- If the current accumulator already contains value against a particular key, return its value as the next accumulator.
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- Otherwise, add the appropriate key-value pair to the accumulator object and return value as the accumulator.
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```js
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const unflattenObject = obj =>{
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return Object.keys(obj).reduce((res , k)=>{
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k.split('.').reduce(function(acc, e, i , keys) {
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return acc[e] || (acc[e] = isNaN(Number(keys[i + 1])) ? (keys.length - 1 === i ? obj[k] : {}) : []);
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}, res)
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return res;
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},{});
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}
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```
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```js
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unflattenObject({ 'a.b.c': 1, d: 1 }); // { a: { b: { c: 1 } }, d: 1 }
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unflattenObject({ 'a.b': 1, 'a.c': 2, d: 3 }); // { a: { b: 1, c: 2 }, d: 3 }
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unflattenObject({ 'a.b.0': 8, d: 3 }) //{ a: { b: [ 8 ] }, d: 3 }
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```
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