In the following code, why can I access the variable x.b? Shouldn't it have a local scope?
CODE
function x() {
var a = 3;
}
x.b = 8;
console.log(x.a);
console.log(x.b);
OUTPUT
undefined
8
3 Answers
When you use var to declare a within x's constructor, a is mark as private, however when you do x.b you are essentially saying - add the property b to the object x.
Hence when you do x.b, technically speaking you are accessing object x's property b, which is 8.
2 Comments
Samuel Toh
@torazaburo correct.
x is just a plain old function. I thought I saw the new keyword somewhere the last time... Hmm I must be tired :(Javascript considers x.b as a global object. so you can access it even inside the function like:
x.b = 8;
function x() {
var a = 3;
alert(x.b)
}
x();
console.log(x.a);
console.log(x.b);
But make sure you specify x.b before function declaration.
whereas object a is specified inside the function x() which makes it private thats why you are getting undefined result for console.log(x.a);
if you write it like this:
a = 5;
function x() {
var a = 3;
}
x.b = 8;
alert(a);
alert(x.b);
you will get results as bellow:
5
8
for javascript a and x.a are two separate objects.
Comments
You have defined x.b to 8 and it becomes a global var. Which means you can access it from anywhere.
So the x() is a function which has its own scope. So you can't access the vars inside a function scope in the mentioned way. However you can access the 'a' by doing this and calling the x function.
function x() {
var a = 3;
return a;
}
xandx.bwere defined in global scope. So why do you expect them to have "local scope"?