函数内部的javascript类变量表示未定义的ES6

class Auto {
  printauto() {
    var type = "2 wheeler";
    var color = "green";
    console.log("Car type is="+this.type+" "+" and color="+this.color);
 }
}

var a = new Auto();
a.printauto();

为什么输出未定义？

汽车类型=未定义且颜色=未定义

解决方法:

仅仅通过声明变量就不会将变量附加到类上下文.您必须明确：

class Auto {
  printauto() {
    this.type = "2 wheeler"; // explicitly attach to `this`
    this.color = "green";    // same here
    console.log("Car type is="+this.type+" "+" and color="+this.color);
 }
}

new Auto().printauto();

构造函数通常是进行此类初始化的最佳位置：

class Auto {
  constructor() {
    this.type = "2 wheeler"; // explicitly attach to `this`
    this.color = "green";    // same here
  }
  printauto() {
    console.log("Car type is="+this.type+" "+" and color="+this.color);
 }
}

new Auto().printauto();

标签：es6-class,javascript
来源： https://codeday.me/bug/20191111/2019789.html