📄 ch6_examp7.htm

📁 javascript source code part1

💻 HTM

字号:

<HTML>
<HEAD>

<SCRIPT LANGUAGE=JavaScript>

function butRemoveWed_onclick() 
{
   if (document.form1.theDay.options[2].text == "Wednesday") 
   {
      document.form1.theDay.options[2] = null;
   } 
   else 
   {
      alert('There is no Wednesday here!');
   }
}

function butAddWed_onclick() 
{
   if (document.form1.theDay.options[2].text != "Wednesday") 
   {
      var indexCounter;
      var days = document.form1.theDay;
      var lastoption = new Option();
      days.options[6] = lastoption;

      for (indexCounter = 6;indexCounter > 2; indexCounter--)
      {
      days.options[indexCounter].text = days.options[indexCounter - 1].text;
      days.options[indexCounter].value = days.options[indexCounter - 1].value;
      }

      var option = new Option("Wednesday",2);
      days.options[2] = option;
   }
   else 
   {
      alert('Do you want to have TWO Wednesdays?????');
   }
}

</SCRIPT>
</HEAD>
<BODY>

<FORM NAME=form1>
<SELECT NAME=theDay SIZE=5>
   <OPTION VALUE=0 SELECTED>Monday
   <OPTION VALUE=1>Tuesday
   <OPTION VALUE=2>Wednesday
   <OPTION VALUE=3>Thursday
   <OPTION VALUE=4>Friday
   <OPTION VALUE=5>Saturday
   <OPTION VALUE=6>Sunday
</SELECT>
<BR>
<INPUT TYPE="button" VALUE="Remove Wednesday" NAME=butRemoveWed 
   onclick="butRemoveWed_onclick()">
<INPUT TYPE="button" VALUE="Add Wednesday" NAME=butAddWed 
   onclick="butAddWed_onclick()">
<BR>
</FORM>
</BODY>
</HTML>

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