Question

无法读取未定义的 ReactJS 的属性“setState”

2018-07-09

187

javascript reactjs

我试图在函数内部设置 React 中的状态，但是我收到一条错误消息，指出：无法读取未定义的属性“setState”。

下面是我的代码，我在构造函数中调用状态，然后在 addTimes 函数中设置状态并将其绑定到该函数，但是我仍然收到错误。

class Settings extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      times: []
    };

  }
  render(){
    Array.prototype.remove = function() {
        var what, a = arguments, L = a.length, ax;
        while (L && this.length) {
            what = a[--L];
            while ((ax = this.indexOf(what)) !== -1) {
                this.splice(ax, 1);
            }
        }
        return this;
    };

    var currentTicked = [];
    var times =[]
    function addTimes(id){
      var index = times.indexOf(id);
      if (!times.includes(id)) {
        $("input:checkbox[name=time]:checked").each(function(){
          currentTicked.push($(this).val());
          times = times.concat(currentTicked)
          times = jQuery.unique(times);
        });
      } else if(times.includes(id)){
        times.remove(id)
      }
      console.log(times);
      addTimes = () => {
        this.setState({
          times: times
        });
      }
    }

Answer 1

您尚未将函数绑定到类。请尝试在组件类中执行

addTimes = (id) => {
  // code here
}

Mr React

2018-07-09

Answer 2

尝试使用箭头函数：

addTimes = id => {
      var index = times.indexOf(id);
      if (!times.includes(id)) {
        $("input:checkbox[name=time]:checked").each(function(){
          currentTicked.push($(this).val());
          times = times.concat(currentTicked)
          times = jQuery.unique(times);
        });
      } else if(times.includes(id)){
        times.remove(id)
      }
      console.log(times);
      addTimes = () => {
        this.setState({
          times: times
        });
      }
    }

或者，在 addTimes 函数中绑定 this ，如下所示：

constructor(props) {
    super(props);
    this.state = {
      times: []
      this.addTimes = this.addTimes.bind(this);
    };

  }

Answer 3

最好使用 es6 语法。尝试以下代码。

 class Settings extends React.Component {
    constructor(props) {
     super(props);
     this.state = {
       times: []
      };

    let times = [];
    let currentTicked = [];
    this.addTimes = this.addTimes.bind(this);
    }
     addTimes(id) {
        let index = times.indexOf(id);
        if (!times.includes(id)) {
            $("input:checkbox[name=time]:checked").each(function(){
              currentTicked.push($(this).val());
              times = times.concat(currentTicked)
              times = jQuery.unique(times);
            });
          } else if(times.includes(id)){
            times.remove(id)
          }
          this.setState({
            times: times
          });
    }
    render(){
    this.addTimes;
    return (
        Array.prototype.remove = function() {
            var what, a = arguments, L = a.length, ax;
            while (L && this.length) {
                what = a[--L];
                while ((ax = this.indexOf(what)) !== -1) {
                    this.splice(ax, 1);
                }
            }
            return this;
        }
    );
    }
}