reference variable in object literal? [duplicate]

问题:

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?

回答1:

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());

回答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());

回答3:

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