Chapter 7
Function Expressions
WHAT’S IN THIS CHAPTER?
- Function expression characteristics
- Recursion with functions
- Private variables using closures
One of the more powerful, and often confusing, parts of JavaScript is function expressions. As mentioned in Chapter 5, there are two ways to define a function: by function declaration and by function expression. The first, function declaration, has the following form:
function functionName(arg0, arg1, arg2) {
//function body
}
The name of the function follows the function keyword, and this is how the function’s name is assigned. Firefox, Safari, Chrome, and Opera all feature a nonstandard name property on functions exposing the assigned name. This value is always equivalent to the identifier that immediately follows the function keyword:
//works only in Firefox, Safari, Chrome, and Opera alert(functionName.name); //"functionName"
FunctionNameExample01.htm
One of the key characteristics of function declarations is function declaration hoisting, whereby function declarations are read before the code executes. That means a function declaration may appear after code that calls it and still work:
sayHi();
function sayHi(){
alert("Hi!");
}
FunctionDeclarationHoisting01.htm
This example doesn’t throw an error because the function declaration ...
