JavaScript recursive function calls (recursive Funciton call)

The so-called recursive function call is to call its own function.

1 var NULL ; 2 function A () {3     console.log (123); 4     Timerhandler = SetTimeout (A,n)    ; 5 }6A (); 7 // cleartimeout (timerhandler);

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/* Count down to 0 recursively. */var Functionholder = function (counter) {    Console.log (counter);    if (Counter > 0) {        functionholder (counter-1);    }}

　

With this, functionHolder(3); would output 3 2 1 0 . Let's say I did the following:

var copyfunction = Functionholder;

copyFunction(3);would output3 2 1 0As above. If I then changedfunctionHolderAs follows:

Functionholder = function (whatever) {    Console.log ("Stop counting!");}

　　

Then functionHolder(3); would give Stop counting! , as expected.

copyFunction(3);Now gives 3 Stop counting! as it refers functionHolder to and not the function (which it itself points to). This could being desirable in some circumstances, but is there a-to-write the function so it calls itself rather tha n the variable that holds it?

That's, is it possible-to -change-only-the- functionHolder(counter-1); going through all these steps still gives 3 When do 1 0 we call copyFunction(3); ? I tried but that this(counter-1); gives me the error this is not a function .

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Using Named Function Expressions:

You can give a function expression a name actually private and are only visible from inside of the Functio N ifself:

VarFactorial= functionMyself(N) { if  (n <= 1) { return 1  } return n * Myself (n- 1); }typeof myself ===  ' undefined '        

Here myself are visible only inside of the function itself.

You can use this private name to call the function recursively.

See the 13. Function Definition ECMAScript 5 spec:

The Identifier in a functionexpression can is referenced from inside the Functionexpression ' s functionbody to allow the FU Nction to call itself recursively. However, unlike in a functiondeclaration, the Identifier in a functionexpression cannot is referenced from and does not AF Fect the scope enclosing the functionexpression.

Please note this Internet Explorer up to version 8 doesn ' t behave correctly as the name was actually visible in the Enclosi NG variable environment, and it references a duplicate of the actual function (see Patrick DW' s comment below).

JavaScript recursive function calls (recursive Funciton call)