Function
is a block of statements used to reuse the code. Functions are defined using
function keyword
How to define a function?
function
functionName(argument1, argument2....argumentN){
//Block of statements
}
How to call a function?
functionName(argument1,
argument2....argumentN)
A function
can take zero (or) more arguments.
Zero argument function
function
helloWorld(){
document.write("Hello
World");
}
One argument function
function
square(x){
return x*x;
}
Above
function takes a number and return the square of it.
Two-argument function
function
sum(x, y){
return x+y;
}
Above
function calculates the sum of two numbers.
functions.html
<!DOCTYPE html> <html> <head> <title>Functions Example</title> </head> <body> <script type="text/javascript"> function helloWorld() { document.write("Hello World"); } function square(x) { return x * x; } function sum(x, y) { return x + y; } document.write("Square of 5 is " + square(5) + "<br />"); document.write("Sum of 10 and 20 is " + sum(10, 20) + "<br />"); helloWorld(); </script> </body> </html>
Open above
page in browser, you can able to see following lines.
Square of
5 is 25
Sum of 10
and 20 is 30
Hello
World
Method Vs function
If a
function is assigned to the property of object is called method.
What is constructor?
Functions
that are designed to initialize the object are called constructors.
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