26 lines
694 B
Markdown
26 lines
694 B
Markdown
---
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title: Subset of iterable
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type: snippet
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language: javascript
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tags: [array]
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cover: citrus-drink
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dateModified: 2020-10-22T20:24:30+03:00
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---
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Checks if the first iterable is a subset of the second one, excluding duplicate values.
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- Use the `Set` constructor to create a new `Set` object from each iterable.
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- Use `Array.prototype.every()` and `Set.prototype.has()` to check that each value in the first iterable is contained in the second one.
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```js
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const subSet = (a, b) => {
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const sA = new Set(a), sB = new Set(b);
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return [...sA].every(v => sB.has(v));
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};
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```
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```js
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subSet(new Set([1, 2]), new Set([1, 2, 3, 4])); // true
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subSet(new Set([1, 5]), new Set([1, 2, 3, 4])); // false
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```
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