clientY

Write a xHTML program to take input from the user and move the image to the corresponding location(position), using Javascript.

Note: ( CSS – Cascading StyleSheet )
Static Positioning does not have top and left properties, so an image which is positioned as Static can’t be moved.
Absolute positioning: The image moves to the new location according to the values of top and left.
Relative positioning: Here the image moves relative to its original position. From its original position, it applies the new top and left value and moves accordingly.

Video Explaining The Code:

YouTube Link: https://www.youtube.com/watch?v=cJtMtd2QmMM [Watch the Video In Full Screen.]

Write a xhtml program, and use the form input tags and accept two values from the user. Using document.getElementById, get those user entered values and assign it to two variables.
Similarly, using the div tags id, change the style information and assign the user entered values to div tags top and left position whenever user hits the “move” button.

Source Code: (move.html)

 
<html>
 <head><title> Move Image </title>
 
 <style type="text/css">
  #kids { position: relative; top: 200px; left: 400px; }
 </style>
 
 <script type="text/javascript">
 
  function moveIt()
 {
var x = document.getElementById("x").value;
var y = document.getElementById("y").value;
 
var kids = document.getElementById("kids").style;
 
kids.top = x + "px";
kids.left = y  + "px";
 
 }
 
 </script>
 </head>
 <body>
 
<form>
X axis: <input type="text" id="x"><br />
Y axis: <input type="text" id="y"><br />
<input type="button" value=" Move " onclick="moveIt()" >
</form>
 
<div id="kids">
  <img 
  src="http://technotip.org/wp-content/themes/NewsDen/images/logo.gif" 
  width="220" height="42">
</div>
 
 </body>
</html>

Fun Application Code:
We have made some minor changes to the above code to get the x and y co-ordinates from the cursor position automatically.

Here, we do not accept input directly from the user. We have removed the html form using html comments(

<!--  Comments -->

) and invoke the javascript function moveIt when the user moves his mouse on the html document.
When there is onmousemove event, most browsers automatically throw some objects and we accept it in our function(as parameter) and make use of it. Some browsers like Microsoft’s Internet Explorer do not throw the event object automatically, so we assign it manually using the below code

   if( !evnt )
evnt = window.event;

Explanation of above two lines of code:
If evnt does not exist, then assign the event to evnt variable.

Also Make Sure To Watch This Video: Event Object: Javascript

Now using the clientX and clientY or screenX and screenY property of the event object, we track the x and y co-ordinates of the cursor and assign that value to the top and left position of the image(div tag which wraps the image tag).

 
<html>
 <head><title> Move Image </title>
 
 <style type="text/css">
  #kids { position: relative; top: 200px; left: 400px; }
#x, #y { font-size: 24pt; color: red; }
 </style>
 
 <script type="text/javascript">
 
document.onmousemove = moveIt;
 
  function moveIt(evnt)
 {
if( !evnt )
evnt = window.event;
 
var x = evnt.clientX;
var y = evnt.clientY;
 
var kids = document.getElementById("kids").style;
 
kids.top = x + "px";
kids.left = y  + "px";
 
document.getElementById("x").innerHTML = x;
document.getElementById("y").innerHTML = y;
 
 
 }
 
 </script>
 </head>
 <body>
X:<span id="x"></span><br />
Y:<span id="y"></span>
<!--
<form>
X axis: <input type="text" id="x"><br />
Y axis: <input type="text" id="y"><br />
<input type="button" value=" Move " onclick="moveIt()" >
</form>
-->
<div id="kids">
 <img 
 src="http://technotip.org/wp-content/themes/NewsDen/images/logo.gif" 
 width="220" height="42">
</div>
 
 </body>
</html>

Hence, whenever the user move his mouse pointer over the html document the image starts moving according to the new value generated for the each move.

“Browser throws object automatically whenever an event occurs.” This is true with most browsers, except Microsoft’s Internet Explorer.
To solve the browser incompatibility and to make our programs work the same way in all major browsers(including Internet Explorer – IE ), we need to write the coding with little smartness!

What does this program do?
Here we will track the users cursor movement and display the X and Y axis of the cursor position in the browser window.
We will make use of onmousemove event and clientX and clientX properties.

We will also show how to catch the event objects and make proper use of them and how to handle a situation when the event object is not passed automatically.

YouTube Link: https://www.youtube.com/watch?v=UPqPooGsAHs [Watch the Video In Full Screen.]

HTML Code:
Here we have taken a form with two empty input tags. Latter with the help of javascript program we will fill the value of these empty input html tags.

 
<html>
 <head>
  <title> Events In Javascript </title>
  <script type="text/javascript" src="event.js"></script>
 </head>
 <body>
 
  <form>
X axis: <input type="text" id="x"><br />
Y axis: <input type="text" id="y">
 
  </form>
 
 </body>
</html>

To link our html and the javascript files, we need to write this code in the head tag of html file:

   <script type="text/javascript" src="event.js"></script>

Javascript code:

 
document.onmousemove = call;
 
function call(evnt) {
 
if( !evnt )
evnt = window.event;
 
document.getElementById("x").value = evnt.clientX;
document.getElementById("y").value = evnt.clientY;
 
}

Here, when we move our mouse over the html document, call() function is invoked.
If the event object is not automatically passed by the browser i.e., if the browser is internet explorer, then we manually assign the event to evnt object using below code:

 
if( !evnt )
evnt = window.event;

With clientX and clientY property of the event object, we will assign the x axis and y axis value to the empty input tags using its id.

Tag: clientY

Moving Image Inside HTML page: Javascript ( A Small Fun Application )

Event Object: Javascript