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问题：

真奇怪。我在子组件的输入框中输入，当我输入“onChange”方法时，应该将更新发送到父组件。我输入的第一件事未能更新，但随后我输入的任何其他内容都会更新，但与当前输入不同步。

我是 Reactjs 的菜鸟，也不是 JavaScript 的高手，所以我不知道发生了什么。

例子：

这是我的对象的控制台输出，用于更新状态和“setState”之后的新状态

第一次尝试更新value1：

Object {value1: "5"}

Object {value1: "0", value2: "0", value3: "0", opening: "0"}

第二次尝试更新value1：

Object {value1: "55"}
Object {value1: "5", value2: "0", value3: "0", opening: "0"}

如您所见，第一次没有更新。然后第二次部分更新。

代码：

var Calculator = 
    React.createClass({
      getInitialState:function(){
        return {
            inputValues:{
              value1: "0",
              value2: "0",
              value3: "0",
              opening: "0"
            },
            outputValues:{
              buyRate: "0",
              sellRate: "0",
              buyStopLoss: "0",
              buyTopProfit: "0",
              sellStopLoss: "0",
              sellTopProfit: "0"  
            }

        }
    },
    //Not worrying about updating here yet. It' the child component below that is being funky.
    update: function(update){
      console.log("Calculator update was called");
        this.setState(
          update           
        );
     },
      render: function () {
        return (
          <div>
            <div className="grid">
              <div className="col fluid">
                <h2>Input</h2>
                <Input values={this.state.inputValues} onClick={this.handleClick} update={this.update} value1={this.state.value1} value2={this.state.value2} value3={this.state.value3} opening={this.state.opening}/>
              </div>
              <div className="col fluid">
                <h2>Output</h2>
                <Output />
              </div>
            </div>
          </div>
        );
}
});


var Input = 
React.createClass({
   getInitialState:function(){
      return{
        value1 : this.props.values.value1,
        value2 : this.props.values.value2,
        value3 : this.props.values.value3,
        opening : this.props.values.opening
      }
   },
   //Here is the update that is not updating the first time around. 
   update: function(key,value){
      //console.log("Input Update was Called");
      var newState = {};
      newState[key]= value;
      this.setState(newState);
      //console.log(newState);
      //console.log(this.state);
    },
    render:function(){
        return (
                <div>
                <p><InputComponent update={this.update} name="value1" value={this.props.values.value1} /> / <InputComponent update={this.update} name="value2" value={this.props.values.value2}/> / <InputComponent update={this.update} name="value3" value={this.props.values.value3}/></p>
                <p><InputComponent update={this.update} name="value3" value= {this.props.values.opening} /></p>
                </div>
            )
    }
});

var InputComponent = 
React.createClass({
    handleChange: function(){
      //console.log("handleChange was called");
      var newValue = React.findDOMNode(this.refs.text).value.trim();
      //console.log(this.props.name);
      //console.log("newValue =");
      //console.log(newValue);
      this.props.update(this.props.name,newValue);
    },
    render: function() {
        return <input type="text" ref="text" placeholder="Enter Value" onChange={this.handleChange} />;
    }
});
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1 回答 1

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我弄清楚了问题所在。您必须注意这setState()是一个异步调用。我的打印输出在函数返回之前被调用，这就是为什么输出似乎错过了一个字符。如果您想检查您的状态是否正在正确更新，请使用为该方法提供的回调setState(function|object nextState[, function callback])。

例如：

update: function(key,value){
              console.log("Input Update was Called");
              var newState = {};
              newState[key]= value;
              console.log("New state and old state BEFORE update");
              console.log(newState);
              console.log(this.state);
              this.setState(newState,this.printState);

            },
            printState: function()
            {
              console.log("New state AFTER update");
              console.log(this.state);

            },
于 2015-05-12T04:27:23.000 回答