#+title: free function

A free function is a [[file:20210307152738-programming_languages.org][programming language]] construct where a [[file:20210521211721-function_programming.org][function]] is not
bound to a particular object, such as a [[file:20210521211757-method_programming.org][method]].

In the following example, =f= is a free function while =obj.m= is a method
(=obj.m= can reference =this=[fn:1] ):

#+begin_src js
function f() {
    return "f";
}

const obj = {
    m: function () {
        return "m";
    },
};
#+end_src

* Footnotes

[fn:1] This example is somewhat misleading because in [[file:20200720132835-javascript.org][JavaScript]] a free function
can become a method. Consider the following example:

#+begin_src js
function f() {
    return this.name;
}

const obj = {
    name: 'obj',
};

console.log('free func:\t', f());
obj.f = f;

console.log('method:\t', obj.f());
#+end_src

#+RESULTS:
: free func:	 undefined
: method:	 obj
: undefined

Further, in [[file:20200720132835-javascript.org][JavaScript]], =this= can be set in free functions:

#+begin_src js
function f() {
    return `my name is ${this.name}`;
}

console.log(f.call({name: 'foo'}));
#+end_src

#+RESULTS:
: my name is foo
: undefined