Question

If I have this code:

var foo1 = new Foo();
var foo2 = new Foo();

and I want to do this:

function updateFoo1 (foo) 
{
   if (foo === foo1) //If foo is foo1
   {
       //code for processing
       return true;
   }
   else //Foo must be foo2 or another instance of foo not foo1
     return false;
}

Will this work as expected to make sure whether the function argument foo is the same as foo1 and not foo2 or any other instance of the foo class? If not, what should I do to get the result I want?

Answer 1

function Foo(){}
var foo1 = new Foo();
var foo2 = new Foo();
console.log(foo1===foo2); // always false

Object comparison is being done by object’s reference so foo1 returns a different reference and foo2 returns another reference. In your case

function updateFoo1(foo) 
{
    if (foo === foo1)
    {
        //code for processing
        return true;
    }
    else return false;
}
updateFoo1(foo1) // first if condition will work and will return true
updateFoo1(foo2) // else condition will work and will return false

See yourself here.