12 lines
529 B
Markdown
12 lines
529 B
Markdown
### Array includes
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Use `slice()` to offset the array/string and `indexOf()` to check if the value is included.
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Omit the last argument, `fromIndex`, to check the whole array/string.
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In [ES6](http://www.ecma-international.org/ecma-262/7.0/#sec-array.prototype.includes), you can use a similar native `.includes()` function.
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```js
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const includes = (collection, val, fromIndex=0) => collection.slice(fromIndex).indexOf(val) != -1;
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// includes("30-seconds-of-code", "code") -> true
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// includes([1, 2, 3, 4], [1, 2], 1) -> false
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```
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