Help with some JS code

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  • mbuna@yahoo.com
    #1

    Help with some JS code

    I have the following code in a page, but it always returns true.

    if (pagevalue >=1 && pagevalue <= maxpages);
    {
    return true;
    }

    return false;



    I can enter 0 for pagevalue or 10*maxpages for page value and it always
    returns true.

    What am I doing wrong?

    TIA

    Tags: None
    • Evertjan.
      #2
      Re: Help with some JS code

      wrote on 23 feb 2005 in comp.lang.javas cript:
      [color=blue]
      > I have the following code in a page, but it always returns true.
      >
      > if (pagevalue >=1 && pagevalue <= maxpages);
      > {
      > return true;
      >}
      > return false;[/color]

      this is the same as:

      return pagevalue>=1 && pagevalue<=maxp ages;

      [color=blue]
      > I can enter 0 for pagevalue or 10*maxpages for page value and it always
      > returns true.[/color]

      test:

      pagevalue=2;
      maxpages=1;
      r= (pagevalue>=1) && (pagevalue<=max pages);
      alert(r);

      shows: false

      pagevalue=0;
      maxpages=100;
      r= pagevalue>=1 && pagevalue<=maxp ages;
      alert(r);

      shows: false


      --
      Evertjan.
      The Netherlands.
      (Replace all crosses with dots in my emailaddress)

        Comment

        • Erwin Moller
          #3
          Re: Help with some JS code

          mbuna@yahoo.com wrote:
          [color=blue]
          > I have the following code in a page, but it always returns true.
          >
          > if (pagevalue >=1 && pagevalue <= maxpages);
          > {
          > return true;
          > }
          >
          > return false;
          >
          >
          >
          > I can enter 0 for pagevalue or 10*maxpages for page value and it always
          > returns true.
          >
          > What am I doing wrong?
          >
          > TIA[/color]

          Hi,

          I have 3 things to say:
          First, use () to order your logic.

          My guess is that you ment:

          if ( (pagevalue >=1) && (pagevalue <= maxpages) )
          {
          return true;
          } else {
          return false;
          }

          second:
          You wrote:
          if (pagevalue >=1 && pagevalue <= maxpages);

          Did you see the ; at the end?

          Third:
          Even if you used:
          if ( (pagevalue >=1) && (pagevalue <= maxpages) )
          the function should return false for 0 and 10* maxpages.
          It only returns true when it is INBETWEEN (and including) 1 and maxpages.

          Regards,
          Erwin Moller



            Comment

            • mbuna@yahoo.com
              #4
              Re: Help with some JS code

              Neither of those worked. Both caught 0 as invalid but neither caught
              the high end. Here's the full function, it was writen by someone else
              and I'm just trying to make it work.



              function validate(objFrm )
              {
              var maxpages="<?=$n um_pages?>";
              var pno=numchk(objF rm.pageno.value );
              var pagevalue=(objF rm.pageno.value );

              if(pno=="no")
              {
              alert("Enter a number between 1 and "+ maxpages +". You entered "
              + pagevalue +".");
              objFrm.pageno.s elect();
              return false;
              }

              if ( (1 <= pagevalue) && (pagevalue <= maxpages) )
              {
              return true;
              }

              alert("Enter a number between 1 and "+ maxpages +". You entered " +
              pagevalue +".");
              objFrm.pageno.s elect();
              return false;
              }

                Comment

                • Erwin Moller
                  #5
                  Re: Help with some JS code

                  mbuna@yahoo.com wrote:
                  [color=blue]
                  > Neither of those worked. Both caught 0 as invalid but neither caught
                  > the high end. Here's the full function, it was writen by someone else
                  > and I'm just trying to make it work.
                  >[/color]

                  Hi,

                  I made you a simple script, that tests what you try to do.
                  It works as expected.

                  -----------------------------

                  <html>
                  <head>
                  <script type="text/javascript">
                  function test() {
                  var pagevalue = document.forms. testform.myNum. value;
                  var maxpages = document.forms. testform.maxpag es.value;

                  if ( (1 <= pagevalue) && (pagevalue <= maxpages) )
                  {
                  alert ("true!");
                  } else {
                  alert ("false!");
                  }

                  }
                  </script>
                  </head>
                  <body>

                  <form name="testform" >
                  pagevalue: <input type="text" name="myNum">
                  <br>
                  maxpages: <input type="text" name="maxpages" >
                  <br>
                  <input type="button" onClick="test() ;" value="doTest">
                  </form>

                  </body>
                  </html>

                  ---------------------------

                  So I think the problem must be somewhere else.
                  Try adding alerts under:
                  var pno=numchk(objF rm.pageno.value );
                  var pagevalue=(objF rm.pageno.value );

                  to see if pno and pagevalue contain values you expect.
                  Actually, I alway debug by adding alerts, and in 90% of the cases I very
                  quickly find that I don't get the values in my vars that I expected in the
                  first place.

                  Also, casting values to Integer (ParseInt) can help.

                  Hope this helps. :-)

                  Regards,
                  Erwin Moller

                    Comment

                    • denisb
                      #6
                      Re: Help with some JS code

                      <mbuna@yahoo.co m> wrote:[color=blue]
                      > I have the following code in a page, but it always returns true.
                      > What am I doing wrong?[/color]
                      [color=blue]
                      > if (pagevalue >=1 && pagevalue <= maxpages);[/color]
                      just this _______________ _______________ _____^


                      (the ;)

                      --
                      @@@@@
                      E -00 comme on est very beaux dis !
                      ' `) /
                      |\_ =="

                        Comment

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