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fix: use constructor property instead of instanceof

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atomiks
2018-04-12 00:29:40 +10:00
committed by GitHub
parent 15cd005a5f
commit 85f9fab1be
1 changed files with 6 additions and 6 deletions
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12
snippets/is.md
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@ -1,11 +1,11 @@
### is
Checks if the provided value is of the specified type (doesn't work with literals).
Checks if the provided value is of the specified type.
Use the `instanceof` operator to check if the provided value is of the specified `type`.
Ensure the value is not `undefined` or `null` and compare the `constructor` property on the value with `type` to check if the provided value is of the specified `type`.
```js
const is = (type, val) => val instanceof type;
const is = (type, val) => ![, null].includes(val) && val.constructor === type;
```
```js
@ -16,10 +16,10 @@ is(RegExp, /./g); // true
is(Set, new Set()); // true
is(WeakMap, new WeakMap()); // true
is(WeakSet, new WeakSet()); // true
is(String, ''); // false
is(String, ''); // true
is(String, new String('')); // true
is(Number, 1); // false
is(Number, 1); // true
is(Number, new Number(1)); // true
is(Boolean, true); // false
is(Boolean, true); // true
is(Boolean, new Boolean(true)); // true
```