Use Function in Javascript

Question

in the following javascript code I see there's a use of the command function, but it didn't specify the name of the function. What's this all about?

var getReview = function(movie) {
    switch (movie) {

    case "Matrix":
        return "good trip out";
        break;
    case "Princess Bride":
        return "awesome date night movie";
        break;
    case "Welcome to America":
        return "Amjad's favorite";
        break;
    case "Remember the Titans":
        return "love the sports";
        break;
    case "Why do I look like I'm 12?":
        return "The Ryan and Zach story";
        break;
    case "Fighting Kangaroos in the wild":
        return "Token Australian movie for Leng";
        break;
    default:
        return "I don't know!";
    }
};​

Answer 1

It's an anonymous function.

Quoting from the link above:

Anonymous functions are declared using the function operator. You can use the function operator to create a new function wherever it’s valid to put an expression. For example you could declare a new function as a parameter to a function call or to assign a property of another object.

Here’s an example where a function is declared in the regular way using the function statement:

function eatCake() {
    alert("So delicious and moist");
}
eatCake();

Here’s an example where the same function is declared dynamically using the function operator:

var eatCakeAnon = function() {
    alert("So delicious and moist");
};
eatCakeAnon();

Answer 2

It's a function literal. It's exactly¹ like a function, but doesn't have a name; it's just an object, like everything else in JavaScript, with the special part being that you can call it. Here, it's immediately assigned to getReview, so you can call getReview() to call the function.

_{¹ Actually, its definition won't be hoisted, but you don't need to worry about that.}