36 lines
1.0 KiB
Markdown
36 lines
1.0 KiB
Markdown
---
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title: deepClone
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tags: object,recursion,advanced
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---
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Creates a deep clone of an object.
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Clones primitives, arrays and objects, excluding class instances.
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- Use recursion.
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- Check if the passed object is `null` and, if so, return `null`.
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- Use `Object.assign()` and an empty object (`{}`) to create a shallow clone of the original.
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- Use `Object.keys()` and `Array.prototype.forEach()` to determine which key-value pairs need to be deep cloned.
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- If the object is an `Array`, set the `clone`'s `length` to that of the original and use `Array.from(clone)` to create a clone.
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```js
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const deepClone = obj => {
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if (obj === null) return null;
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let clone = Object.assign({}, obj);
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Object.keys(clone).forEach(
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key =>
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(clone[key] =
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typeof obj[key] === 'object' ? deepClone(obj[key]) : obj[key])
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);
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if (Array.isArray(obj)) {
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clone.length = obj.length;
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return Array.from(clone);
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}
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return clone;
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};
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```
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```js
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const a = { foo: 'bar', obj: { a: 1, b: 2 } };
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const b = deepClone(a); // a !== b, a.obj !== b.obj
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```
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