javascript变量声明中的if语句

Question

I have such variable declaration in my JavaScript method on :

var MyVariable = {
    CarMake: "Lexus",
    CarColor: "Black"
}

What I am trying to accomplish is to add some login within MyVariable declaration such as:

    var MyVariable = {
    CarMake: "Lexus",
    if (carType == "sedan") {
        NumberOfDoors: 4,
    }
    CarColor: "Black"
}

Is this possible somehow?

Answer 1

With a one-line object you can't do it. You need to assign it later. But I thnik you can create a class(ES6) and use like

 class Car{ constructor(maker, color, type){ this.maker = maker; this.color = color; if(type === 'sedan'){ this.numberOfDoors = 4; } } } var car = new Car('Lexus','Black','sedan'); console.log(car.numberOfDoors); 

Or use the function syntax

  function Car(maker, color, type){ this.maker = maker; this.color = color; if(type === 'sedan'){ this.numberOfDoors = 4; } } var car = new Car('Lexus','Black','sedan'); console.log(car.numberOfDoors); 

Answer 2

I suppose you could do

var MyVariable = {
  CarMake: "Lexus",
  CarColor: "Black",
  NumberOfDoors: (carType === 'sedan') ? 4 : undefined
}

which is not exactly the same, but close.

---

But how about

var MyVariable = {
  CarMake: "Lexus",
  CarColor: "Black"
}

if (carType === 'sedan') {
    MyVariable.NumberOfDoors = 4
}

You could wrap this into a "factory" function and then do

var MyVariable = makeCar("Lexus", "Black", "sedan") 

Answer 3

You need to create your variable before and add the new attribute after :

var MyVariable = {
   CarMake: "Lexus",
   CarColor: "Black"
}

if (carType == "sedan") {
    MyVariable.NumberOfDoors = 4
}

Answer 4

One way you could do this:

var MyVariable = {
    CarMake: "Lexus",
    CarColor: "Black"
}

if (carType == "sedan") {
    MyVariable.NumberOfDoors = 4;
}