reference variable in object literal? [duplicate]

Question

This question already has an answer here:

• Self-references in object literals / initializers 22 answers

say I have

myfunc({
  var1: 1,
  var2: 2,
})

if i want to have a value that makes use of the current unnamed object, how would I do this?

eg if I wanted

myfunc({
  var1: 1,
  var2: 2,
  var3: this.var1 + this.var2
})

obviously this does not work.

What would the correct syntax be?

Answer 1

You can't do it in the notation you're using. An object literal doesn't have any notion of itself in this context.

Answer 2

You could make var3 a function, and calling it will allow you to use 'this':

x= {
    v1:4,
    v2:5,
    v3:function(){return this.v1 + this.v2;}
};

alert(x.v3());

Answer 3

Unfortunately, that isn't possible. While an object literal is being constructed, no external reference to that object exists until the entire literal is evaluated. The only way to use this at this stage is to use a constructor instead:

function MyObject() {
  this.var1 = 1;
  this.var2 = 2;
  this.var3 = this.var1 + this.var2;
}

myfunc(new MyObject());