JavaScript autopopulate a text box

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  • jambyl
    New Member
    • Oct 2007
    • 8
    #1

    JavaScript autopopulate a text box

    I have a JSP page which has two text boxes.
    I would like to be able to enter a number into the first textbox, and to have that number automatically appear in the second textbox multiplied by 3.
    So if I enter number 1 into the first text box, then I want number 3 appear in the second text box.
    Does anyone know how to do that? Do I need to use JavaScript for that?

    Thank you!
    Tags: None
    • Ferris
      New Member
      • Oct 2007
      • 101
      #2
      hi

      yes,you do need javascript...

      here's the code I write for you:


      [HTML]
      <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
      "http://www.w3.org/TR/html4/loose.dtd">
      <html>
      <head>
      <title>Untitl ed Document</title>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
      </head>
      <script language="javas cript">
      function mul()
      {
      var a = document.getEle mentById("first ").value;
      document.getEle mentById("secon d").setAttribut e("value",a * 3);
      }
      </script>
      <body>
      <input type="text" id="first" onChange="mul() ;" value="0" />
      <input type="text" id="second" value="0" />
      </body>
      </html>


      [/HTML]

        Comment

        • jambyl
          New Member
          • Oct 2007
          • 8
          #3
          Ferris,
          Thank you for such a quick reply!!! You code works good, but right now after typing a number in my first text box - I have to click somewhere or hit TAB, Only then the second text box is multiplied by three.
          Is there a way to have the number in second text box change without me leaving the first box?

          Kind regards.

            Comment

            • Ferris
              New Member
              • Oct 2007
              • 101
              #4
              hi

              change line 16 :
              <input type="text" id="first" onChange="mul() ;" value="0" />

              into

              <input type="text" id="first" onKeyUp="mul(); " value="0" />

                Comment

                • jambyl
                  New Member
                  • Oct 2007
                  • 8
                  #5
                  Ferris,
                  This works great!!!

                  Thank you!!!

                    Comment

                    • helimeef
                      New Member
                      • Sep 2007
                      • 77
                      #6
                      Originally posted by Ferris
                      hi

                      change line 16 :
                      <input type="text" id="first" onChange="mul() ;" value="0" />

                      into

                      <input type="text" id="first" onKeyUp="mul(); " value="0" />
                      Don't do that Ferris! IE doesn't support key events, use a setInterval every few seconds to fill er up.

                        Comment

                        • Ferris
                          New Member
                          • Oct 2007
                          • 101
                          #7
                          Originally posted by helimeef
                          Don't do that Ferris! IE doesn't support key events, use a setInterval every few seconds to fill er up.

                          thanks for telling me that,but I have tested my code in both IE and Firefox,they works well.

                            Comment

                            • acoder
                              Recognized Expert MVP
                              • Nov 2006
                              • 16032
                              #8
                              Originally posted by helimeef
                              Don't do that Ferris! IE doesn't support key events, use a setInterval every few seconds to fill er up.
                              What makes you say that? Can you give an example that doesn't work?

                                Comment

                                • helimeef
                                  New Member
                                  • Sep 2007
                                  • 77
                                  #9
                                  Originally posted by acoder
                                  What makes you say that? Can you give an example that doesn't work?
                                  Sorry I guess it does. I think it's IE6 that doesn't support. Maybe just starting to have nightmares about IE :p

                                    Comment

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