CODEWITHSUNDEEP
javascript
user2507818
user2507818

Reputation: 3037

issue with the reference function in javascript

<script>
//bob first initialization
var bob = function()
{
    console.log('bob');
};

//set jan to bob via reference
var jan = bob;

//set bob to another function
bob = function()
{
    console.log('newbob');
};

jan(); //console.logs 'bob'
bob(); //console.logs 'newbob'


</script>

Question:

why jan(); outputs bob, not newbob? since jan() is the reference of bob()

Upvotes: 0

Views: 37

Answers (2)

Francisco Meza
Francisco Meza

Reputation: 883

jan and bob are just two variables that happened to point to the same function at one point in time, but the assignment of a new value to one of them doesn't have any effect on the value assigned to the other. It's like:

var a = 1;
var b = a; // a and b evaluate to 1
var a = 2; // a evaluates to 2, b evaluates to 1 (a's
           // assignment has no effect on b)

Upvotes: 0

Quentin
Quentin

Reputation: 943097

After var jan = bob;, both jan and bob are references to the same function.

bob = function() {} assigns a reference to a new function to bob

jan still contains a reference to the original function.

i.e. You are changing the value of the variable, you aren't changing the function that the variable referred to.

To compare:

var a = { f: function () { console.log(1); } };
var b = a;
a.f = function () { console.log(2); };

Now a and b contain references to the same object. The object contains a reference to a function. When you assign a new function to that object property the a.f and b.f both change because a and b are still both references to the same object.

Upvotes: 4

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