Question

I’m having difficulties understanding behavior of Javascript.

Code:

function getPosition(element){
    var position = {
        x:$(".line div").has(element).index(),
        y:$(".line").has(element).index()
    };
    console.log(position.y);
    console.log(position)
    return position;
}

Now while calling it from function I’m getting results like this:

0

Object
x: 8
y: 3

What I don’t understand is how is it possible to change object attributes when trying to access it via object reference, but not directly.

But when I call same function from console I get this:

0

Object
x: 8
y: 0

This is the same element passed to function. And it seems that it fails always when X or Y is 0(zero), when it’s another number it’s ok.

Could anyone explain what I’m doing wrong? Or is it somekind of JS bug? O_o

EDIT:

So I finally found out what the problem was. I always thought that I was passing values but unfortunately I was wrong all the time. During some searches on stackoverflow, I found topic about JS values and references.

If anyone is interested and too lazy to read the topic, you can look at this example. It’s pretty much self explanatory.

function test(){
    var a = 5;
    var b = a; //b now has value of 5
    console.log("a:"+a+":b:"+b);
    b = 4;//a still has value of 5 and b is assinged to 4
    console.log("a:"+a+":b:"+b);
    var c = {val:1};
    var d = c; //d now has reference to c
    d.val = 2; //c.val changes because it is a reference
    console.log(c);
}

EDIT2:
oh and by the way, how can I mark my question as answered?

Answer 1

So I finally found out what the problem was. I always thought that I was passing values but unfortunately I was wrong all the time. During some searches on stackoverflow, I found topic about JS values and references.

If anyone is interested and too lazy to read the topic, you can look at this example. It’s pretty much self explanatory.

function test(){
    var a = 5;
    var b = a; //b now has value of 5
    console.log("a:"+a+":b:"+b);
    b = 4;//a still has value of 5 and b is assinged to 4
    console.log("a:"+a+":b:"+b);
    var c = {val:1};
    var d = c; //d now has reference to c
    d.val = 2; //c.val changes because it is a reference
    console.log(c);
}