CODEWITHSUNDEEP
javascript
Amir
Amir

Reputation: 1259

How do I convert a function name into a string

I have a function from an object, lets say Object.MyFunc. I need to send this function name into another function like so: doSomething("Object.MyFunc");

any advise?

Upvotes: 10

Views: 5648

Answers (6)

RJ Cuthbertson
RJ Cuthbertson

Reputation: 1528

This is an old question, but in ES6 this ability is provided via the Function.name property. The ECMAScript 2015 Language Specification defines how this property is added to a Function instance:

9.2.11 SetFunctionName (F, name, prefix)

The abstract operation SetFunctionName requires a Function argument F, a String or Symbol argument name and optionally a String argument prefix. This operation adds a name property to F by performing the following steps: ...

Unfortunately, this hasn't yet been implemented in all major browsers: It's listed here as not supported in all IE versions, and only partially supported in all other major browsers (with Edge 13 having the best, albeit still partial, support currently).

Upvotes: 10

KooiInc
KooiInc

Reputation: 122996

Perhaps you mean something like this?

function getFn(fnName){
    for (var l in yourObj){
      if (l === fnName && yourObj[l] instanceof Function){
        return [ l, yourObj[l] ];
      }
    }
    return [fnName ,'not found'];
}

the loop iterates through the object and delivers an array containing the method name and a pointer to the method (or an error message).

Upvotes: 1

Russell Leggett
Russell Leggett

Reputation: 8883

As others have pointed out, it is most likely that whatever you're trying to do can be done better a different way. However, if you truly need to find the name of a function, there is one fairly simple way to do this, but it will not work in all cases.

//returns the name of the function func on the object obj
function getFuncName(obj, func){
  for(var funcName in obj){
    if(obj[funcName] === func){
      return funcName;
    }
  }
}

alert(getFuncName(Object, Object.MyFunc)); //alerts "MyFunc"

The limitation here, is that you'll need both the object and the function, and the function will have to be iterable - meaning that it can't be a built in function.

Upvotes: 1

Ali
Ali

Reputation: 267307

If you have this function:

function test()
{
  alert('here');
}

You can call it in this way:

function testTest(func)
{
   func();
}

testTest(test);

Upvotes: -1

carl
carl

Reputation: 50564

There isn't a really good way to get the function name. In JavaScript, you can have anonymous functions and therefore don't have a decent way to name them.

In any case, you might have some luck using arguments.callee.toSring(). For example:

function foo() {
    alert("I am " + arguments.callee.toString());
}

But, this is poor because not all functions have names and some browsers may append implementation-specific details to this string.

But, perhaps you are trying to do something else besides getting the name? If you want to eventually call the function, you can actually pass the function itself. This is called a lambda function. For example:

function foo(inFunc) {
    inFunc();
}

foo(function() { alert("foo"); });

The above code creates an anonymous function that pops up an alert. It is then passed to the foo function which just calls whatever function is passed into it.

Upvotes: 4

Paolo Bergantino
Paolo Bergantino

Reputation: 488724

If you are trying to call MyFunc from within doSomething, you can just pass the actual function:

var someObject = new Object();
someObject.MyFunc = function() { alert('test'); }
function doSomething(func) {
    func();
}
doSomething(someObject.MyFunc);

Upvotes: 3

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