In some Javascript libraries published on the web I find code like this:
var foo = function foo() {};
To me this seems like a mistake. I only learned two ways to define a function:
var foo = function() {};
or
function foo() {};
The combination of both seems redundant.
Also, it does not seem to work. E.g.
var foo = function bar() {};
foo(); // works.
bar(); // -> Uncaught ReferenceError: bar is not defined
Is there any reason to repeat the function name after the "function" keyword? It seems wrong to me, but I have seen it more than once, so I am wondering.
Answer TLDR
Long answer and more details in the linked QA.
Short answer: The function name does have an effect: - as a local symbol inside the scope of the declared function. - as name property stored on the function itself.
var foo = function bar() {
console.assert(foo === bar);
}
console.assert('undefined' === typeof bar);
console.assert('bar' === foo.name);
// trigger assert() inside the function.
foo();
// the following might be browser-dependent:
var anon = function () {}
console.assert('anon' === anon.name);
var obj = {method: function () {}};
console.assert('method' === obj.method.name);
obj.method2 = function () {};
console.assert('' === obj.method2.name);
