javascript - get key name inside of it`s value function -

how key names it`s value nameless function?

what /*some code */ 'foo'

var obj = {     foo: function () {              console.log('error found in ' + /* code */);          } };  obj.foo(); // 'error found in foo' 

by iterating on properties of this using for..in can test against arguments.callee

var o = {     foo: function () {         var k, found, pname = 'unknown';         (k in this) if (this[k] === arguments.callee) {             found = true;             break;         }         if (found) pname = k;         console.log('error found in ' + pname);     },     bar: "something else" };  o.foo(); // error found in foo 

please note arguments.callee is forbidden in strict mode es5 spec.

in case need named function expression,

var o = {     foo: function fizzbuzz() {         var k, found, pname = 'unknown';         (k in this) if (this[k] === fizzbuzz) {             found = true;             break;         }         if (found) pname = k;         console.log('error found in ' + pname);     },     bar: "something else" };  o.foo(); // error found in foo 

finally,

• if doing things can't guarantee enumerability for..in not work, take here
• if you've changed this, there no way function know want without passing reference object in way