Javascript Functions

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Functions

 /*
  a function is reusable piece of code.
  function is the keyword
  function can be defined once, and used many time
 */
  //function defincation
  function add(a, b)
  {
   c = a + b
   return c
  }
  
  //function call
  document.write(add(2, 5))
  document.write("<BR>")
  document.write(add(20, 50))
  
  //alert is javascript builtin function for displaying messages
  function showme()
  {
   alert("Hello! I am an alert")
  }
  
  function printme()
  {
   print()
  }
  function confirmation()
  {
   var answer = confirm("Are you sure you want to leave this page")
   if(answer)
   {
    alert("Bye Bye")
    close()
   }
   else
   {
    alert("Thanks for sticking around")
   }
  }
 
      <script type="text/javascript">
/*
a function is reusable piece of code.
function is the keyword
function can be defined once, and used many time
*/
//function defincation
function add(a, b)
{
c = a + b
return c
}

//function call
document.write(add(2, 5))
document.write("<BR>")
document.write(add(20, 50))

//alert is javascript builtin function for displaying messages
function showme()
{
alert("Hello! I am an alert")
}

function printme()
{
print()
}
function confirmation()
{
var answer = confirm("Are you sure you want to leave this page")
if(answer)
{
alert("Bye Bye")
close()
}
else
{
alert("Thanks for sticking around")
}
}

</script>

     

 

Going to next page

 function newpage()
 {
  window.location = "http://www.google.com"
 }
      <script type="text/javascript">
function newpage()
{
window.location = "http://www.google.com"
}
</script>

Javascript Functions

0 comments

Functions

 /*
  a function is reusable piece of code.
  function is the keyword
  function can be defined once, and used many time
 */
  //function defincation
  function add(a, b)
  {
   c = a + b
   return c
  }
  
  //function call
  document.write(add(2, 5))
  document.write("<BR>")
  document.write(add(20, 50))
  
  //alert is javascript builtin function for displaying messages
  function showme()
  {
   alert("Hello! I am an alert")
  }
  
  function printme()
  {
   print()
  }
  function confirmation()
  {
   var answer = confirm("Are you sure you want to leave this page")
   if(answer)
   {
    alert("Bye Bye")
    close()
   }
   else
   {
    alert("Thanks for sticking around")
   }
  }
 
      <script type="text/javascript">
/*
a function is reusable piece of code.
function is the keyword
function can be defined once, and used many time
*/
//function defincation
function add(a, b)
{
c = a + b
return c
}

//function call
document.write(add(2, 5))
document.write("<BR>")
document.write(add(20, 50))

//alert is javascript builtin function for displaying messages
function showme()
{
alert("Hello! I am an alert")
}

function printme()
{
print()
}
function confirmation()
{
var answer = confirm("Are you sure you want to leave this page")
if(answer)
{
alert("Bye Bye")
close()
}
else
{
alert("Thanks for sticking around")
}
}

</script>

     

 

Going to next page

 function newpage()
 {
  window.location = "http://www.google.com"
 }
      <script type="text/javascript">
function newpage()
{
window.location = "http://www.google.com"
}
</script>

Javascript Functions

JavaScript function is reusable piece of code that can be coded once and reused many times. For example, we can create a function that will either switch ON or OFF the lights and then reuse this function by switching the button to ON or OFF

Syntax of Creating a JavaScript Function

function SWITCH(INPUT)
{
Read the INPUT  and perform any action, for example SWITCH ON or SWITCH OFF
}

  • function is a JavaScript keyword

Example of JavaScript Function Creation

  • In above example we created a function and named it add. This function is expecting two value
  • function is a JavaScript keyword, so we must type it ‘as it is’
  • Function values also known as input parameters are always enclosed in parentheses ( ) and separated by comma
  • When creating a function we can specify as many input values as we like.
  • The action of a function is defined in curly braces { }
  • This function will add value of a to value of b and then save the result in c
  • This function will provide us the answer by using a keyword return

Syntax of Using a JavaScript Function

SWITCH(INPUT)

  • In order to use a function simply type the name of function and pass it the values it is expecting from us.
  • For switching lights function it’s expecting one value from us, either ON or OFF
  • Once a function is created, we can use it as many times as we like

Example of JavaScript Function Usage

  • In above example we are using (also known as calling) the function add
  • we are sending two input values (also known as parameters) of 4 and 5 to our function.
  • function parameter are enclosed in parentheses ( ) and separated by a comma ,
  • the above example will result in 9