Question

I was wondering how to declare new variables by accessing variable values in the same object. I tried this.x and object.x. Both say cannot read property of undefined.

e.g.

var board = {
    width: 188, 
    height: 110, 
    left: (320 - board.width)/2,
    top: (480 - this.height)/8, 
};

Answer 1

You can’t do that because board is not defined until after the object is constructed and the assignment executes. (Also, this is not defined outside a function.) You’ll have to use more than one statement.

var board = { width : 188, height : 110 };
board.left = (320 - board.width) / 2;
board.top = (480 - board.height) / 8;