Skip to main content

Javascript event based programming



If we perform any action on the HTML element then the event will be raised.
for example, if we click on Button then click is the event for Button.
.......................................................................................................................................
Javascript provides multiple sets of events according to HTML elements:-
EVENT LIST OF JAVASCRIPT:-
1 onload :-  when the page will start to load then onload event method will be called.
Example of Onlod:-
Create Script to change page background when the page will be loaded?
<!DOCTYPE html>
<html>
<head>
<title></title>
<script>
     function fun()
     {
        document.getElementById("b").style.backgroundColor='cyan';
     }
     function fun1()
     {
      alert("GET huge discount in DEVOPS");
     }
</script>
</head>
<body id="b" onload="fun();fun1()">
</body>
</html>
2 onclick:-
It is the most important command because it is used to click a button, reset, submit, image, div, hyperlink element and perform an action.
<script>
function display()
{
}
</script>
<input type="button" onclick= "display()"    />
Create JAVASCRIPT to change page background according to Button Click, if We click on Red button then Red Color, Green Button then Green Color, Blue button then Blue Color.
<!DOCTYPE html>
<html>
<head>
<title></title>
<script>
function fun()
{
document.getElementById("b").style.backgroundColor='orange';

}
     function fun1()
     {
       document.getElementById("b").style.backgroundColor="red";
     }
     function fun2()
     {
      document.getElementById("b").style.backgroundColor="green";
     }
     function fun3()
     {
      document.getElementById("b").style.backgroundColor="blue";
     }
</script>
</head>
<body id="b" onload="fun()">
<input type="button" value="Red" onclick="fun1()" />
<br>
<br>
<input type="button" value="Green" onclick="fun2()" />
<br>
<br>
<input type="button" value="Blue" onclick="fun3()" />
</body>
</html>
Create Event For Addition Program?
3 mouseover:-
When we mouse over the button, image or hyperlink then this event will be called.
4 onmouseout:-
when we remove mouse position from a button, image or hyperlink then this will be called.
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
function fun1()
{
           document.getElementById("img").style.width="300px";
           document.getElementById("img").style.height="300px";
}
function fun2()
{
          document.getElementById("img").style.width="100px";
          document.getElementById("img").style.height="100px";
} 

</script>
</head>
<body>

<img src="logo.png" id="img" onmouseover="fun1()" onmouseout="fun2()"   width="100" height="100" />
</body>
</html>
Example 2:-
<!DOCTYPE html>
<html>
<head>
    <title></title>
    <script>
     function fun1()
     {
            //alert("fun1");
           document.getElementById("im").src ="img2.png";
     }
     function fun2()
     {
            //alert("fun2");
           document.getElementById("im").src ="img3.jpg";
     }
    
     function fun4()
     {
         document.getElementById("im").src ="logo.png";
     }
    </script>
</head>
<body>
<img src="img1.jpg"  width="200px" height="250px" onmouseover="fun1()" onmouseout="fun2()" onmousemove="fun3()" onmouseenter="fun4()" id="im" />
<br>
<br>
</body>
</html>
5 onkeyup:-
when we presss any key then first up key will work
6 onkeydown:-
when we relase key button then it will work.
<!DOCTYPE html>
<html>
<head>
    <title></title>
    <script>
     function showdata(a)
     {
         document.getElementById("board").innerHTML=a;
     }
     function changecolor(a)
     {
         document.getElementById("board").style.backgroundColor=a;
     }
    </script>
</head>
<body>

<div id="board" style="background-color: black;color:white;width:300px;height: 200px;border:2px solid red;float:left;" >
</div>
<select onchange="changecolor(this.value)" >
<option value="Red">Red</option>
<option value="Green">Green</option>
<option value="Blue">Blue</option>
</select>
<br>
<br>
<div style="clear: left"></div>
Type here
<br>
<textarea id="txt" onkeyup="showdata(this.value)" rows="5" cols="20">
</textarea>
</body>
</html>
7 onblur:-
It will be called when the cursor will be removed from textfield.
8 onfocus:-
It will be called when cursor will be assigned into textfield
Example of ONBLUR and ONFOCUS
<!DOCTYPE html>
<html>
<head>
<title></title>
<script>
       function fun1()
       {
           document.getElementById("txt1").style.backgroundColor='red';
       }
        function fun2()
       {
           document.getElementById("txt2").style.backgroundColor='green';
       }
       function fun3()
       {
        document.getElementById("txt1").style.backgroundColor='';
        document.getElementById("txt2").style.backgroundColor='';
       }
</script>
</head>
<body>
<input type="text" id="txt1" onblur="fun1()" onfocus="fun3()" />
<br>
<br>
    <input type="text" id="txt2" onfocus="fun2()" />
</body>
</html>
9 onchange:-
RadioButton CheckBox:-
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
function fun(a)
{
//alert(a);
document.getElementById("res").innerHTML= "Selected Course is "+a;
}
</script>
</head>
<body>
 <h1>Select Course</h1>
 <input type="radio" name="r1" id="r1" value="C" onchange="fun(this.value)">C
 <br>
 <input type="radio" name="r1" id="r1" value="CPP" onchange="fun(this.value)">CPP
 <br>
 <input type="radio" name="r1" id="r1" value="DS" onchange="fun(this.value)">DS
 <br>
  <span id="res"></span>
</body>
</html>
..................................................................................................................

It is used to manage event operation in ListBox,SelectBox,RadioButton and CheckBox  .
CheckBox Complete Code:-
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
function fun()
{
        var s=document.frm.chk;
        s1="";
          for(i=0;i<s.length;i++)
          {
          if(s[i].checked)
          {
          s1=s1+s[i].value;
          }
          }
         document.getElementById("res").innerHTML=s1;
}
</script>
</head>
<body>
<form name="frm">
<input type="checkbox" id="chk[]" name="chk" value="C" onchange="fun()" />C
<br>
<br>
<input type="checkbox" id="chk[]" name="chk" value="CPP" onchange="fun()"  />CPP
<br>
<br>
<input type="checkbox" id="chk[]" name="chk" value="DS" onchange="fun()"  />DS
<br>
<br>
<span id="res"></span>
</form>
</body>
</html>
....................................................................................................
JavaScript Example for DropDownList and ListBox:-
We can select only single item
<select id="xyz">
<option value="Value Field ">Display Item</option>
</select>
ListBox:-
We can select multiple item's.
<select id="xyz" multiple="true">
<option value="Value Field ">Display Item</option>
</select>
Complete Explanation of DropDownlist,ListBox ,CheckedLIST using JS?
<!DOCTYPE html>
<html>
<head>
<title></title>
<style type="text/css">
li
{
list-style-type: none;
}
li:hover
{
background-color: gray;
}
</style>
<script>
      function fun(a)
      {
           document.getElementById("res").innerHTML=a;

      }
      function fun1()
      {
      course="";
      for(i=0;i<document.getElementById("lst[]").length;i++)
      {
            if(document.getElementById("lst[]")[i].selected)
            {
            course = course+document.getElementById("lst[]")[i].value+" ";
            }
      }
      document.getElementById("res").innerHTML=course;
      }
        function fun2()
      {
      course="";
      //console.log(document.frm.chk.length);
      for(i=0;i<document.frm.chk.length;i++)
      {
            if(document.frm.chk[i].checked)
            {
            course = course+document.frm.chk[i].value+" ";
            }
      }
      document.getElementById("res").innerHTML=course;
      }
</script>
</head>
<body>
<select onchange="fun(this.value)">

<option value="C">C</option>
<option value="CPP">CPP</option>
<option value="DS">DS</option>
    <option value="JAVA">JAVA</option>
    <option value=".NET">.NET</option>
</select>
<br>
<br>
<br>
<select id="lst[]"   onchange="fun1()" multiple="true">

<option value="C">C</option>
<option value="CPP">CPP</option>
<option value="DS">DS</option>
    <option value="JAVA">JAVA</option>
    <option value=".NET">.NET</option>
</select>
<div id="res">
</div>
<form name="frm">
<ul>
<li> <input type="checkbox" name="chk" id="chk[]" value="C" onchange="fun2()">C</li>
<li> <input type="checkbox" name="chk" id="chk[]" value="CPP" onchange="fun2()">CPP</li>
<li> <input type="checkbox" name="chk" id="chk[]" value="DS" onchange="fun2()">DS</li>
<li> <input type="checkbox" name="chk"id="chk[]" value="JAVA" onchange="fun2()">JAVA</li>
<li> <input type="checkbox" name="chk" id="chk[]" value=".NET" onchange="fun2()">.NET</li>
</ul>
</form>
</body>
</html>

Labels:

Comments

Post a Comment

POST Answer of Questions and ASK to Doubt

Popular posts from this blog

Uncontrolled form input in React-JS

  Uncontrolled form input in React-JS? If we want to take input from users without any separate event handling then we can uncontrolled the data binding technique. The uncontrolled input is similar to the traditional HTML form inputs. The DOM itself handles the form data. Here, the HTML elements maintain their own state that will be updated when the input value changes. To write an uncontrolled component, you need to use a ref to get form values from the DOM. In other words, there is no need to write an event handler for every state update. You can use a ref to access the input field value of the form from the DOM. Example of Uncontrolled Form Input:- import React from "react" ; export class Info extends React . Component {     constructor ( props )     {         super ( props );         this . fun = this . fun . bind ( this ); //event method binding         this . input = React . createRef ();...
Post a Comment
Read more

JSP Page design using Internal CSS

  JSP is used to design the user interface of an application, CSS is used to provide set of properties. Jsp provide proper page template to create user interface of dynamic web application. We can write CSS using three different ways 1)  inline CSS:-   we will write CSS tag under HTML elements <div style="width:200px; height:100px; background-color:green;"></div> 2)  Internal CSS:-  we will write CSS under <style> block. <style type="text/css"> #abc { width:200px;  height:100px;  background-color:green; } </style> <div id="abc"></div> 3) External CSS:-  we will write CSS to create a separate file and link it into HTML Web pages. create a separate file and named it style.css #abc { width:200px;  height:100px;  background-color:green; } go into Jsp page and link style.css <link href="style.css"  type="text/css" rel="stylesheet"   /> <div id="abc"> </div> Exam...
Post a Comment
Read more

JDBC using JSP and Servlet

JDBC means Java Database Connectivity ,It is intermediates from Application to database. JDBC has different type of divers and provides to communicate from database server. JDBC contain four different type of approach to communicate with Database Type 1:- JDBC-ODBC Driver Type2:- JDBC Vendor specific Type3 :- JDBC Network Specific Type4:- JDBC Client-Server based Driver  or JAVA thin driver:- Mostly we prefer Type 4 type of Driver to communicate with database server. Step for JDBC:- 1  Create Database using MYSQL ,ORACLE ,MS-SQL or any other database 2   Create Table using database server 3   Create Form according to database table 4  Submit Form and get form data into servlet 5  write JDBC Code:-     5.1)   import package    import java.sql.*     5.2)  Add JDBC Driver according to database ide tools     5.3)  call driver in program         ...
4 comments
Read more