54 lines
1.3 KiB
Markdown
54 lines
1.3 KiB
Markdown
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---
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title: Bind 'this' to a Class Method
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---
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## Bind 'this' to a Class Method
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If a method on JavaScript `class` need to access some internal `state` of the instance, like `this.state`, the method need to be bound to the instance of the `class`. A more detailed description of 'this' binding can be found [here](https://github.com/getify/You-Dont-Know-JS/blob/master/this%20%26%20object%20prototypes/ch2.md)
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### Hint 1
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Like many things in programming, there is more than one way to bind this. For this challenge we are going to stick with constructor binding.
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```js
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class MyClass {
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constructor() {
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this.myMethod = this.myMethod.bind(this);
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}
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myMethod() {
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// whatever myMethod does
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}
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}
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```
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## Spoiler
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```jsx
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class MyComponent extends React.Component {
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constructor(props) {
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super(props);
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this.state = {
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itemCount: 0
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};
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// change code below this line
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this.addItem = this.addItem.bind(this);
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// change code above this line
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}
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addItem() {
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this.setState({
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itemCount: this.state.itemCount + 1
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});
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}
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render() {
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return (
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<div>
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{ /* change code below this line */ }
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<button onClick={this.addItem}>Click Me</button>
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{ /* change code above this line */ }
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<h1>Current Item Count: {this.state.itemCount}</h1>
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</div>
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);
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}
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}
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```
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