Problem with default checked checkboxes: Javascript_问答_开发者

Problem with default checked checkboxes: Javascript

开发者 https://www.devze.com 2023-03-28 06:51 出处：网络

I have created the following function to check the first value of the check box when loading a page -

function defaultCheck(){
      document.checkBoxForm.list[0].checked = true;
      var val=document.checkBoxForm.list[0].value;
      showtotal[0] = document.checkBoxForm.list[0].value;
      show(val);
      editVal();
      //alert('ajhsdjha');
 }

I have used the function in html page load by <body onload="defaultCheck()">.

My problem is - when there are more than one values in the list the function by default selects the first one but when there is just one value in the开发者_StackOverflow list, it does not select it. The values of check boxes are dynamically retrieved from database by -

 <?php
     while($row=mysql_fetch_array($levelq)) {?>
        <input type='checkbox' name="list" value="<?=$row['tag']?>"  
               id="<?=$row['tag']?>" onclick="" />
        <?  echo $row['tag'].' '.'<br/><br/>'; 
     }
?>

I have no idea why is it behaving so weird. Can anyone help me out please?

I'll bet money that the problem is the use of [0]. Have you considered removing that?

But, that said, you shouldn't be doing this in JS anyway, you should do this in PHP:

 $checked = 'checked="true"';
 while($row=mysql_fetch_array($levelq)) {
    // you also may wish to consider using list[] instead of list. That will make
    // reading the value much easier in PHP
    ?>
    <input type='checkbox' name="list" value="<?=$row['tag']?>"  
           id="<?=$row['tag']?>" onclick="" <?=$checked?> />
    <?  echo $row['tag'].' '.'<br/><br/>'; 
    $checked = "";
 }

Like @cwallenpoole said, you should be doing this in PHP.

If you still want to do it in JS, here you go:

function defaultCheck(){
      if(document.checkBoxForm.list.length > 1) {
          document.checkBoxForm.list[0].checked = true;
          var val=document.checkBoxForm.list[0].value;
          showtotal[0] = document.checkBoxForm.list[0].value;
      } else {
          document.checkBoxForm.list.checked=true;
          var val=document.checkBoxForm.list.value;
           showtotal[0] = document.checkBoxForm.list.value;
      }
      show(val);
      editVal();
      //alert('ajhsdjha');
 }

This happens because, when there is only 1 checkbox, list refers to that checkbox, NOT the array of checkboxes