30 lines
901 B
Markdown
30 lines
901 B
Markdown
---
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title: Bind object method
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tags: function,object
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expertise: advanced
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cover: blog_images/oven-paddle.jpg
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firstSeen: 2018-01-24T14:22:43+02:00
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lastUpdated: 2020-10-18T23:04:45+03:00
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---
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Creates a function that invokes the method at a given key of an object, optionally prepending any additional supplied parameters to the arguments.
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- Return a `function` that uses `Function.prototype.apply()` to bind `context[fn]` to `context`.
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- Use the spread operator (`...`) to prepend any additional supplied parameters to the arguments.
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```js
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const bindKey = (context, fn, ...boundArgs) => (...args) =>
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context[fn].apply(context, [...boundArgs, ...args]);
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```
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```js
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const freddy = {
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user: 'fred',
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greet: function(greeting, punctuation) {
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return greeting + ' ' + this.user + punctuation;
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}
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};
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const freddyBound = bindKey(freddy, 'greet');
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console.log(freddyBound('hi', '!')); // 'hi fred!'
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```
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