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:
Example
<script>
var x;
x="Hello";
function demo()
{
document.write(x);
}
demo();
</script>
var x;
x="Hello";
function demo()
{
document.write(x);
}
demo();
</script>
<
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":
Example
Calculate the product of two numbers, and return the result:
var x = myFunction(4, 3);
// Function is called, return value will end up in x
function myFunction(a, b) {
return a * b; // Function returns the product of a and b
}
function myFunction(a, b) {
return a * b; // Function returns the product of a and b
}