Function expressions:
// anonymous function expression
var anonymous = function () {
return true;
};
// named function expression
var named = function named() {
return true;
};
// immediately-invoked function expression (IIFE)
(function () {
console.log('Welcome to the Internet. Please follow me.');
}());
Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad news bears.
Note: ECMA-262 defines a block as a list of statements. A function declaration is not a statement. Read ECMA-262’s note on this issue.
// bad
if (currentUser) {
function test() {
console.log('Nope.');
}
}
// good
var test;
if (currentUser) {
test = function test() {
console.log('Yup.');
};
}
Never name a parameter arguments. This will take precedence over the arguments object that is given to every function scope.
// bad
function nope(name, options, arguments) {
// ...stuff...
}
// good
function yup(name, options, args) {
// ...stuff...
}