Read: 06 - Programming with JavaScript:
JavaScript Functions
A JavaScript function is a block of code designed to perform a particular task.
A JavaScript function is executed when “something” invokes it (calls it).
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)
Function Return
When JavaScript reaches a return statement, the function will stop executing.
The () Operator Invokes the Function
Using the example above, toCelsius refers to the function object, and toCelsius() refers to the function result.
Accessing a function without () will return the function object instead of the function result.
Example:
function toCelsius(fahrenheit) {
return (5/9) * (fahrenheit-32);
} document.getElementById(“demo”).innerHTML = toCelsius;
Local Variables
Variables declared within a JavaScript function, become LOCAL to the function.
Local variables can only be accessed from within the function.
Logic of functions:
