1.3 KiB
1.3 KiB
title |
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Bind 'this' to a Class Method |
Bind 'this' to a Class Method
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
Hint 1
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.
class MyClass {
constructor() {
this.myMethod = this.myMethod.bind(this);
}
myMethod() {
// whatever myMethod does
}
}
Spoiler
class MyComponent extends React.Component {
constructor(props) {
super(props);
this.state = {
itemCount: 0
};
// change code below this line
this.addItem = this.addItem.bind(this);
// change code above this line
}
addItem() {
this.setState({
itemCount: this.state.itemCount + 1
});
}
render() {
return (
<div>
{ /* change code below this line */ }
<button onClick={this.addItem}>Click Me</button>
{ /* change code above this line */ }
<h1>Current Item Count: {this.state.itemCount}</h1>
</div>
);
}
}