使用动态值在对象中设置值

Question

First, here is my code:

var lastUsedId = '';
var object = {
    element: lastElement()
};

function lastElement() {
    return lastUsedId;
}

lastUsedId = 123;

console.log(object); // returns `{element: ""}` and should `{element: 123}`

As you can see, I have defined object with key element which should contain last used element's ID. Problem is that I don't know that ID yet it comes to print the result. I can't change the value like object.element = 123 because of my robust application, so don't send comments like that. For this question, it has to bee structured like that.

My question is: can I set the value like function, which returns the variable with content changed afterward? Maybe it is stupid question, but when it is not possible just say it and I will try to find other way.

Answer 1

Not sure this is what you want, but you can use a getter for that:

 var lastUsedId = ''; var object = { get element() { return lastElement() } }; function lastElement() { return lastUsedId; } lastUsedId = 123; console.log(object); lastUsedId = 456; console.log(object); 

Answer 2

can I set the value like function, which returns the variable with content changed afterward?

Why not keep the value as a function only

var obj = {
    element: lastElement
};
console.log( obj.element() ); //this will invoke the method to get the latest value