javaScript.passValueTricks.js - Different condition when passing primitive value and object(and other reference types) to function.

javaScript.passValueTricks.js

function myfunction(b, context) {
    // x is equal to 4
    context.b = 5;
    //alert(this);
    return context;
    //alert("x1: "+x);
    // x is now equal to 5
}

var x = {
    'b': 4
};
alert(x.b); // x is equal to 4
var xx = myfunction('b', x);
alert(xx.b); // x is 5
alert("x1: " + x.b); // x is 5 too


///////////  primitive value not work 
// because they are immutable and are passed by value
function myfunction2(b) {
    // x is equal to 4
   b = 5;
}

var x2 = 4;
alert(x2); // x is equal to 4

myfunction2(x2);
alert(x2); //not changed