1
我想知道为什么,如果我修改此行{this.increaseQty.bind(this)}
到{this.increaseQty}
,控制台会提示遗漏的类型错误:无法读取的不确定代替遗漏的类型错误财产“的setState”:this.setState不是一个函数(...)?如果未设置绑定,则不应该将this
作为窗口对象?未设置绑定时,为什么`this`不是指窗口对象?
export default class CartItem extends React.Component {
constructor(props) {
super(props);
this.state = {
qty: props.initialQty,
total: 0
};
}
componentWillMount() {
this.recalculateTotal();
}
increaseQty() {
this.setState({qty: this.state.qty + 1}, this.recalculateTotal);
}
decreaseQty() {
let newQty = this.state.qty > 0 ? this.state.qty - 1 : 0;
this.setState({qty: newQty}, this.recalculateTotal);
}
recalculateTotal() {
this.setState({total: this.state.qty * this.props.price});
}
render() {
return <article className="row large-4">
<figure className="text-center">
<p>
<img src={this.props.image}/>
</p>
<figcaption>
<h2>{this.props.title}</h2>
</figcaption>
</figure>
<p className="large-4 column"><strong>Quantity: {this.state.qty}</strong></p>
<p className="large-4 column">
<button onClick={this.increaseQty.bind(this)} className="button success">+</button>
<button onClick={this.decreaseQty.bind(this)} className="button alert">-</button>
</p>
<p className="large-4 column"><strong>Price per item:</strong> ${this.props.price}</p>
<h3 className="large-12 column text-center">
Total: ${this.state.total}
</h3>
</article>;
}
}
在ES6中,默认情况下你处于严格模式,所以这将是'undefined'。 – Ben