reactjs - 将多个参数传递给 React 中的事件处理程序

Question

所以我试图让 React 使用 ES6 语法。在 ES5 中，我使用了 setInitialState，但没有使用函数绑定(bind)语法的构造函数。我有一个任意的价格列表，我希望当输入元素更改时状态也会更改。但正确的价格必须改变。

我什至不太确定这是正确的方法。有人可以告诉我最新的方法吗？

这是我的代码:

import React, {Component} from 'react'
import 'bootstrap/dist/css/bootstrap.css';

export default class PriceTable extends Component {
  constructor(props, context) {
    super(props, context);

    this.state = {
      pid: this.props.pid || "12345",
      name: this.props.name || "name",
      prices: this.props.prices || [
        {count: 1, desc: 'one', price: 8.25},
        {count: 6, desc: 'six', price: 7.60},
        {count: 12, desc: 'twelve', price: 6.953}
      ]
    };

    this.setPid = this.setPid.bind(this);
    this.setName = this.setName.bind(this);
    this.setCount = this.setCount.bind(this, i);
    this.setDesc = this.setDesc.bind(this, i);
    this.setPrice = this.setPrice.bind(this, i);
    this.logDebug = this.logDebug.bind(this);
  }

  setPid(e) {
    this.setState({pid: e.target.value})
  }

  setName(e) {
    this.setState({name: e.target.value})
  }

  setCount(i, e) {
    var newPrices = this.state.prices
    newPrices[i].count = e.target.value
    this.setState({prices: newPrices})
  }

  setDesc(i, e) {
    var newPrices = this.state.prices
    newPrices[i].sec = e.target.value
    this.setState({prices: newPrices})
  }

  setPrice(i, e) {
    var newPrices = this.state.prices
    newPrices[i].price = e.target.value
    this.setState({prices: newPrices})
  }

  _renderPriceRow(price, i) {
    return (
      <tr key={i}>
        <td >
          <input type="text" className="form-control" defaultValue={price.count} onChange={this.setCount(this, i).bind(this, i)}/>
        </td>
        <td >
          <input type="text" className="form-control" defaultValue={price.desc} onChange={this.setDesc(this, i).bind(this, i)}/>
        </td>
        <td >
          <input type="text" className="form-control" defaultValue={price.price} onChange={this.setPrice(this, i).bind(this, i)}/>
        </td>
      </tr>
    );
  }

  render() {
    return (
      <div className="row">
       ...
      </div>
    );
  }
}

这就是错误......

PriceTable.jsx:21 Uncaught ReferenceError: i is not defined
    at new PriceTable (PriceTable.jsx:21)

Answer 1

您错误地绑定(bind)了函数

在你的构造函数中，你不需要指定参数，你只需要像 this.setDesc = this.setDesc.bind(this); 那样绑定(bind)它。

此外，在 onChange 中，当您想要将参数传递给函数时，您可以使用绑定(bind)指定它，而不是作为参数传递并再次绑定(bind)它们。

onChange={this.setDesc.bind(this, i)}

整个代码看起来像这样

import React, {Component} from 'react'
import 'bootstrap/dist/css/bootstrap.css';

export default class PriceTable extends Component {
  constructor(props, context) {
    super(props, context);

    this.state = {
      pid: this.props.pid || "12345",
      name: this.props.name || "name",
      prices: this.props.prices || [
        {count: 1, desc: 'one', price: 8.25},
        {count: 6, desc: 'six', price: 7.60},
        {count: 12, desc: 'twelve', price: 6.953}
      ]
    };

    this.setPid = this.setPid.bind(this);
    this.setName = this.setName.bind(this);
    this.setCount = this.setCount.bind(this);
    this.setDesc = this.setDesc.bind(this);
    this.setPrice = this.setPrice.bind(this);
    this.logDebug = this.logDebug.bind(this);
    this._renderPriceRow = this._renderPriceRow.bind(this);
  }

  setPid(e) {
    this.setState({pid: e.target.value})
  }

  setName(e) {
    this.setState({name: e.target.value})
  }

  setCount(i, e) {
    var newPrices = this.state.prices
    newPrices[i].count = e.target.value
    this.setState({prices: newPrices})
  }

  setDesc(i, e) {
    var newPrices = this.state.prices
    newPrices[i].sec = e.target.value
    this.setState({prices: newPrices})
  }

  setPrice(i, e) {
    var newPrices = this.state.prices
    newPrices[i].price = e.target.value
    this.setState({prices: newPrices})
  }

  _renderPriceRow(price, i) {
    return (
      <tr key={i}>
        <td >
          <input type="text" className="form-control" defaultValue={price.count} onChange={this.setCount.bind(this, i)}/>
        </td>
        <td >
          <input type="text" className="form-control" defaultValue={price.desc} onChange={this.setDesc.bind(this, i)}/>
        </td>
        <td >
          <input type="text" className="form-control" defaultValue={price.price} onChange={this.setPrice.bind(this, i)}/>
        </td>
      </tr>
    );
  }

  render() {
    return (
      <div className="row">
       ...
      </div>
    );
  }
}

您还可以使用 Arrow functions 传递参数，例如

onChange={(e) => this.setDesc(e,  i)}