JavaScript-传递对象之间的值

4 回答

• 1

  如果您更改此代码，它将正常工作

  this.fuel = this.fuel + addingfuel;
  

  至

  this.fuel = this.fuel + (addingfuel || 0);
  

  回复于 2024-05-05T20:50:46+08:00
• 0

  你必须用你的 tank(addingfuel) 函数传递 addingfuel 其他明智的 addingfuel 包含 undefined 所以最后它会显示 go 而不是 stop .

  N.B addingfuel 的值是 string 所以你要像_41629那样把它投射到 integer 否则你的 this.fuel === 0 条件会失败

  试试这个，

  var toyota = {
    make: "Toyota",
    model: "Corolla",
    fuel: 0,
    tank: function(addingfuel) {
      this.fuel = this.fuel + parseInt(addingfuel);
    },
    start: function() {
      if (this.fuel === 0) {
        alert("stop");
      } else {
        alert("go");
      }
    },
  };
  var addingfuel = prompt("Please enter fuel added", "liter");
  toyota.tank(addingfuel); // you need to pass this otherwise it is undefined
  toyota.start();
  

  回复于 2024-05-05T20:50:46+08:00
• 0

  window. prompt 返回字符串类型作为返回值 . 这就是为什么当你将 fuel （数字）添加到 addingfuel （字符串）时，它会导致 "00" 并且您的条件失败 .

  为了解决此问题，您应该在使用该值之前将字符串转换为数字 .

  tank: function(addingfuel) {
    var numberValue = parseFloat(addingfuel, 10);
    numberValue = isNaN(numberValue) ? 0 : numberValue
    this.fuel = this.fuel + numberValue;
  }
  

  回复于 2024-05-05T20:50:46+08:00
• 1

  您需要稍微更改一下代码

  var toyota = {
    make: "Toyota",
    model: "Corolla",
    fuel: 0,
    tank: function(addingfuel) {
      this.fuel = this.fuel + (addingfuel || 0);
    },
    start: function() {
      if (this.fuel === 0) {
        alert("stop");
      } else {
        alert("go");
      }
    },
  };
  

  Explanation 当你在调用toyota.tank（）时没有传递任何内容时，这会将参数视为未定义，并使用数字附加undefined会给你NaN

  0 + undefined
  

  回复于 2024-05-05T20:50:46+08:00