在对象属性由另一个函数分配后访问

Question

I'm new to Javascript, and I'm learning how to use OOP principals. I'm stuck on assigning object properties and then accessing them later. Let's say I have this function that assigns properties to an object "Car".

function assignProps()
{
Car.size="small";
Car.cost="expensive";
}

The object Car with empty properties because they are assigned from the function.

var Car =
{
size:"",
cost:"",
returnSize: function()
            {
           return this.size;
            },
returnCost: function()
            {
           return this.cost;
            },

}

Now, I want to call the function that assigned the value, and then access Car's properties. I tried doing this, but it obviously failed:

function accessProps()
{

assignProps();
console.log(Car.returnSize());
console.log(Car.returnCost());

}

Any help would be appreciated. I have a feeling that this might have to do with constructors or prototypes, but since there are so many ways to create custom objects in Javascript, the documentations are very confusing.

EDIT: By "fail" I mean that it outputs the blank instead of the newly assigned value EDIT: I tried doing it this way as well, and it yielded the same result.

Answer 1

You have some errors in your code:

var Car = {
   size:"",
   cost:""
}

And if you look at this fiddle: http://jsfiddle.net/JskBy/ It works as expected.

Full code:

function assignProps() {
    Car.size="small";
    Car.cost="expensive";
}

var Car ={
    size:"",
    cost:""
}
function accessProps(){
  assignProps();
  console.log(Car.size);
}

assignProps();
accessProps();

Answer 2

汽车对象初始化时出现语法错误，应为

var Car = { size: "", cost: "" };

Answer 3

Line 18, column 14: Extra comma.

Line 20, column 2: Missing semicolon.

Try to get a developing tool with JSLint/JSHint built-in (eg Notepad++ with add-on), it might help you with debugging problems like this.