Example of JavaScript functions

JavaScript Function Syntax
A JavaScript function is defined with the function keyword, followed by a name, followed by parentheses ().

Function names can contain letters, digits, underscores, and dollar signs (same rules as variables).

The parentheses may include parameter names separated by commas:
(parameter1, parameter2, …)

The code to be executed, by the function, is placed inside curly brackets: {}
Function Invocation
The code inside the function will execute when “something” invokes (calls) the function:

When an event occurs (when a user clicks a button)
When it is invoked (called) from JavaScript code
Automatically (self invoked)
You will learn a lot more about function invocation later in this tutorial.

Function Return

When JavaScript reaches a return statement, the function will stop executing.

If the function was invoked from a statement, JavaScript will “return” to execute the code after the invoking statement.

Functions often compute a return value. The return value is “returned” back to the “caller”:

Here is a simple scripts to perform a calculation and return the desirable result


This example calls a function which performs a calculation, and returns the result:

JS function example 1

Returned result:

This example calls a function which performs a calculation, and returns the result:


Example 2:JavaScript Numbers

JavaScript numbers can be written with, or without decimals and
extra large or extra small numbers can be written with scientific (exponent) notation:

IS numbers


See results


Example 3: Convert Fahrenheit to Celsius



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