How To Refer Itself In A Function Regardless Of Extenal Variable Changes?

I have a function which has other functions defined: var A = function(n) { console.log(n + A.num()); } A.num = function() { return 5; } I want to change the name to B and dele

Solution 1:

You can always refer to the current function using its explicit name (if it has one).

So, change the definition, to name the function, and refer to it using that:

var A = function currentFunction(n) {
  console.log(n + currentFunction.num());
}
A.num = function() {
  return 5;
}

var B = A;
A = undefined;
B(10); //15

console.log(typeof currentFunction) //undefined, function name is local

Note: the abovementioned approach won't work if the function is named implicitly, but will continue to work if the function is renamed via fn.name

---

Alternatively, if the function isn't an arrow function, you can also use arguments.callee, that will work even with anonymous functions, but its use isn't recommended:

var A = function (n) {
  console.log(n + arguments.callee.num());
}
A.num = function() {
  return 5;
}

var B = A;
A = undefined;
B(10); //15

Unfortunately, none of the above will work with arrow functions, if you want to refer to itself, use a named bound function expression instead.

Solution 2:

actually that's normal, because in js you can't really copy object

// Define object bar
var bar = {
   x : 'Hi'
}
console.log(bar.x);  //Hi

// Assign it to foo
var foo = bar;
console.log(foo.x);  //Hi

//But
foo.x = 'Hello!! Im foo.';
console.log(foo.x);  //Hello!! Im foo.
console.log(bar.x);  //Hello!! Im foo.

bar.x = "Nice to meet you foo!!";
console.log(foo.x);  //Nice to meet you foo!!
console.log(bar.x);  //Nice to meet you foo!!

you have to return a new one with the same value as the last

var foo = {...bar};

and this is not working because B is always calling 'num' from A that doesn't exist, One way to sever the parity would be stringify the initial function, then use a function constructor to create the clone after replacing the 'A' by 'B' but tell me more why are you facing this problem ?

Solution 3:

var A = function(n) {
  if(!this.num){
  console.log("This is not available coz obj is not created");
  console.log("Below error is for testing purpose");
  }
  let a=this.num(n);
  console.log(a);
}
//use prototype here 
//A.num = function() {
A.prototype.num=function(n){
  return n+5;
}
//use new to create object 
new A(5);
var B = A;
A = undefined;
//use new to create object 
new B(6);

B(5);//lets try without using new keyword

.as-console-wrapper { max-height: 100% !important; top: 0; }