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Thread: Explain this javascript

  1. #1
    Join Date
    Jun 2013
    Posts
    33

    Explain this javascript

    This javascript is for horizantly moving text. I could not understand this code. pls explain in details....Thanks...

    <script language="javascript">
    <!--
    var bannerID=0
    function text(msg,ctrlwidth) {
    msg = " --- "+msg
    newmsg = msg
    while (newmsg.length < ctrlwidth) {
    newmsg += msg
    }
    document.write ('<FORM NAME="Scrolltext">');
    document.write ('<CENTER><INPUT NAME="text" VALUE= "'+newmsg+'" SIZE= '+ctrlwidth+' ></CENTER>');
    document.write ('</FORM>');
    var bannerID = null
    rollmsg()
    }
    function rollmsg() {
    NowMsg = document.Scrolltext.text.value
    NowMsg = NowMsg.substring(1,NowMsg.length)+NowMsg.substring(0,1)
    document.Scrolltext.text.value = NowMsg
    bannerID = setTimeout("rollmsg()",100)//change the number 100 to represent the speed of the scroll. The larger the number the slower it moves
    }
    // -->
    </script>

  2. #2
    Join Date
    Feb 2012
    Location
    Tallahassee, FL
    Posts
    280
    Here is the code, with comments. Good luck.
    Code:
    <script language="javascript">
            <!--
            var bannerID=0
            function text(msg,ctrlwidth) {
                //Prepend hyphens to the inputted text
                msg = " --- "+msg;
                //Set the newmsg, which will be used for length of the whole message
                newmsg = msg;
                while (newmsg.length < ctrlwidth) {
                    //While the newmsg is shorther than the maxlength, ctrlwidth, that you privided, append the string
                    newmsg += msg;
                }
                //Put the container for the input on the page
                document.write ('<FORM NAME="Scrolltext">');
                //Put a text-box on the page.  Set the width of that textbox to the maxwidth you provided
                document.write ('<CENTER><INPUT NAME="text" VALUE= "'+newmsg+'" SIZE= '+ctrlwidth+' ></CENTER>');
                //Close the form tag
                document.write ('</FORM>');
                //This doesn't have any effect on anything, you could delete it and it would still work, so I'll comment it out.
                var bannerID = null;
                //Inititate phase 2 (call the other function)
                rollmsg()
            }
            function rollmsg() {
                //Figures out what is showing right now.
                NowMsg = document.Scrolltext.text.value
                //Make what needs to be showing by cutting off the first letter of what is showing and appending the sting to itself but mising the last letter.
                NowMsg = NowMsg.substring(1,NowMsg.length)+NowMsg.substring(0,1)
                //Make the textbox have the new value
                document.Scrolltext.text.value = NowMsg
                //I dont know why this banner ID is here.
                /*bannerID = */setTimeout("rollmsg()",100)//change the number 100 to represent the speed of the scroll. The larger the number the slower it moves
            }
            // -->
        </script>

  3. #3
    Join Date
    Jul 2013
    Posts
    66
    It should be noted that this script was probably written over a decade ago (or by someone who didn't learn anything since over a decade ago). It is littered with out-dated stuff and I would strongly advise not to use this piece of crap code. Sorry for the strong words, but by today's standards it's just true. A few notes:

    - the language attribute was deprecated at least since HTML 4.01
    - using html comments surrounding the javascript became obsolete with browsers such as IE 2 (released in 1995!)
    - document.write should be avoided in favor of DOM methods
    Last edited by Airblader; 08-01-2013 at 02:51 PM.

  4. #4
    Join Date
    Jun 2013
    Posts
    33
    Thanks, NoEffinWay. Thanks for help. But can i use paragraph (<p>) tag instead of <form> tag. If yes how to add "newmsg"value to <p> tag?
    I want a moving text without textbox or anything.
    Thanks.

  5. #5
    Join Date
    Jan 2004
    Location
    chertsey, a small town s.w. of london, england.
    Posts
    1,457
    Hi there dhirajkumar.41,

    here is a rather more modern method fo you to try...
    Code:
    
    <!DOCTYPE html>
    <html lang="en">
    <head>
    
    <meta charset="utf-8">
    
    <title>ticker tex</title>
    
    <style>
    body {
        background-color:rgb(241,241,241);
     }
    #marquee {
        padding:10px;
        border:1px solid rgb(160,160,160);
        border-radius:10px;
        margin:16px auto;
        background-color:rgb(255,255,255);
        box-shadow:inset 0 0 10px rgba(0,0,0,0.4),0 0 10px rgba(0,0,0,0.4);
        font-size:20px;
        color:rgb(108,108,108);
        text-align:center;
        cursor:pointer;
     }
    .fl {
        float:left;
     }
    .lspcg {
        letter-spacing:5px;
     }
    </style>
    
    <script>
    (function() {
       'use strict';
    
    /***************************** editable values *******************************/
    
       var msg='Lorem ipsum dolor sit amet, consectetuer adipiscing elit. ';
       var speed=100;
    
    /*****************************************************************************/
    
       var obj;
       var pos=0;
       var st=null;
    
    function init(){ 
       
       obj=document.getElementById('marquee');
       obj.className='fl lspcg';
       obj.style.width=obj.offsetWidth+'px';
       obj.className='lspcg';
    
       scrollText();
    
    obj.onmouseover=function() {
       clearTimeout(st);
       obj.firstChild.nodeValue=msg;
       obj.className='';
       return;
     }
    obj.onmouseout=function() {
       obj.className='lspcg';
       scrollText();
      }
     }
    
    function scrollText(){
    
       obj.firstChild.nodeValue=
       msg.substring(pos,msg.length)+msg.substring(0,pos);
    
       pos+=2;
    if(pos>msg.length) {
       pos=0;
     }
      st=setTimeout(function(){scrollText()},speed);
     }
    
       window.addEventListener?
       window.addEventListener('load',init,false):
       window.attachEvent('onload',init);
    
    })();
    </script>
    
    </head>
    <body>
    
    <div id="marquee" class="fl">
    Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
    </div>
    
    </body>
    </html>
    coothead

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