Can I create function parameters like string?

Question

I am trying to delve into functions and in the example of the site MDN Web Docs they have the following example:

var math = {
  'factit': function factorial(n) {
    console.log(n)
    if (n <= 1) {
      return 1;
    }
    return n * factorial(n - 1);
  }
};

math.factit(3) //3;2;1;

In that part of the code 'factit': function factorial(n) {} it was here that I did not understand, because in the codes that I see it is usually like this factit: function(){} which is the object parameter and the object value and in the example in that part 'factit' is a parameter, but is a string?

Answer 1

This is not a parameter, even less it belongs to a function. This is an object, if it were a parameter it would be in parentheses, for example the n there in the function factorial() is a parameter.

This is a member of an object, and yes, it can be used as a symbol in the code or as string, gives the same. So what you’re defining there is a member of an object whose type is a function (function) and its value is just a function, perhaps from that comes the confusion, the function is there as the value and has nothing to do with what it is talking about.

A JS object is created as a array associative, a map, therefore in fact it is a structure that has elements with a key and a value. As it is an object all keys are strings same. There is a syntactic sugar that makes you not need to write the quotes or the object indexer.

Then the same code can be written like this:

var math = {
    factit: function factorial(n) {
        console.log(n)
        if (n <= 1) return 1;
        return n * factorial(n - 1);
    }
};

math['factit'](3) //3;2;1;

I put in the Github for future reference.

Note that I have now reversed the use of syntactic sugar. Now in the field definition I did not use quotes in the name, but when calling the method inside the object I used the Apas and indexer to access the field. As the field is a function I might call it, but this is another mechanism, by coincidence it is there, but it could be the same thing with a value whatever is not a function.

The ideal is to always use syntactic sugar unless you have a very good reason not to do so which is almost always a mistake (there are a few legitimate advanced situations, but there is a lot of abuse). The example of the documentation could have made the statement of the object as I did here, but the call there is in the best shape even.