Call and argument passing

[Matej]

Hello , i have a questions

if i got it right , if i use call or apply , the function or object which is this code executed in with inherit specific properties ,

for example

function a(args){    b.apply(this,arguments); // here we said , that function a should inherit stuffs from function B , it does inherit alert("lol") , but why doesnt it inherit x also?     alert(x);} function b(){   alert("lol");var x=9;} a(); [/code] and second questionargument passing can be done by value or refference , value is usually primitive varriable like string or numberand refference is usually object. If i set [code]var g=9function call(x){x+=9;}call(g)[/code]

var g inside function equals 18 , but globaly variable g still equals 9 , so why when i set

var person=new Object;function call(x){x.name="david"}call(person)

here if i call person.name outside of the function it equals "david" bcs i created copy of "person" and both of them reffer to one object in header;

so why when i do this

http://jsfiddle.net/nj5a84hm/ person.name="lol" and not "kek"? object should be passed by refference.

(if objects are passed by value , person.name should be undeffined)

 

Could someone explain it to me? thanks for answers

Edited October 1, 2014 by Matej

[justsomeguy]

Using Function.apply or Function.call is not about inheritance, it is about scope. In function a you're just saying to call function b in the same scope where function a is running. Declaring the local variable x inside b does not also declare it inside a, once b ends then x gets destroyed because it is a local variable inside b. If you used this.x inside both functions then they would refer to the same thing, because they are both running in the same scope.

person.name="lol" and not "kek"? object should be passed by refference.

It does get passed by reference, but when you make x a new object you are no longer changing the object that was passed to the function, now it's a different object. The object outside of the function does not get changed when you set the variable x to a new object inside the function.

[Matej]

thanks for answers , but when var x gets destroyed after b ends how come alert does not get destroyed?

[thescientist]

alert is a native method (on the window object), and not a local variable

http://www.w3schools.com/jsref/met_win_alert.asp