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Function Naming Rules
JavaScript naming rules for functions are as follows:
Function names can contain letters (a-z, A-Z), digits (0-9), underscores (_), and dollar signs ($).
Function names must begin with a letter, an underscore (_), or a dollar sign ($) but cannot start with a digit.
Function names are case-sensitive.
JavaScript keywords cannot be used as function names.
Function names cannot contain spaces.
A list of the arguments for the function, enclosed in parentheses and separated by commas.
Creating a Function
Defining a function in JavaScript takes multiple important elements that determine the functionality of the
function and how it may be utilized. Below is a detailed walk-through of how to define a function in JavaScript,
step-by-step:
Step 1: The function Keyword is used to declare a function in JavaScript, we begin with the function keyword.
This informs JavaScript that we are about to declare a new function.
Step 2: We provide a name for the function. Function names may include letters, numbers, underscores (_),
and dollar signs ($). Function names, however, should not begin with a number.
Step 3: We can define parameters. Parameters are holders that serve as variables for values that will be
used when the function is invoked. A function may have zero or more parameters. The parameters
are utilized within the function body and are considered local variables.
Step 4: The function body is defined with curly braces {}. Here you need to insert the code that should be
processed upon calling the function.
Step 5: If you wish for the function to return a value when invoked, you can make use of the return keyword.
The return command stops the execution of the function and, if desired, sends a value back to the
location where the function was invoked.
The syntax of a function is as follows:
function name(parameter1, parameter2, parameter3)
{
// code to be executed
}
For example:
function greet(name) {
document.write("Hello, " + name + "!");
}
In this example:
greet is the function name.
name is a parameter, which is used inside the function to greet a person.
The function uses document.write to output a message.
Calling the Function: To execute the function and pass an argument to the parameter, we invoke it by its name
and pass an argument (value):
hello("Alice");
198 Touchpad Web Applications (Ver. 2.0)-XII

