[英]constructor call a member function that return a value in javascript
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
this.age();
}
age() {
return 99;
}
}
myCar = new Car("Ford", 2014);
document.getElementById("demo").innerHTML =
"My car is " + myCar + " years old.";
//結果
我的車是 [object Object] 歲了。
為什么變量 myCar 沒有值 99 ? 相反,它包含 [object,object]
考慮到您當前的代碼:
class Car {
constructor(name, year) {
this.name = name;
this.year = year;
this.age();
}
age() {
// date = new Date(); // This will not work
let date = new Date(); // This will work
return 99;
}
}
myCar = new Car("Ford", 2014);
document.getElementById("demo").innerHTML =
"My car is " + myCar + " years old.";
myCar
是對象。 如果你想返回 99 你需要調用myCar.age()
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