29 lines
916 B
Markdown
29 lines
916 B
Markdown
---
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title: functions
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tags: object,function,intermediate
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---
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Returns an array of function property names from own (and optionally inherited) enumerable properties of an object.
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Use `Object.keys(obj)` to iterate over the object's own properties.
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If `inherited` is `true`, use `Object.get.PrototypeOf(obj)` to also get the object's inherited properties.
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Use `Array.prototype.filter()` to keep only those properties that are functions.
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Omit the second argument, `inherited`, to not include inherited properties by default.
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```js
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const functions = (obj, inherited = false) =>
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(inherited
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? [...Object.keys(obj), ...Object.keys(Object.getPrototypeOf(obj))]
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: Object.keys(obj)
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).filter(key => typeof obj[key] === 'function');
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```
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```js
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function Foo() {
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this.a = () => 1;
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this.b = () => 2;
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}
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Foo.prototype.c = () => 3;
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functions(new Foo()); // ['a', 'b']
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functions(new Foo(), true); // ['a', 'b', 'c']
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``` |