如何使用jQuery onchange事件在HTML中添加和删除属性？

Question

Hello guys I just want to ask how can i create a jquery that can detect the user input and assign an attribute or remove an attribute based on the user input. My scenario is I have a table with 4 columns. First is a dropdown. And the rest are textboxes which are readonly. The default option for dropdown is NULL or empty. If the user choose from the dropdown, the 2 texboxes should not be readonly. On that process I don't have an error but if the user set back again to NULL. The 2 textboxes won't go back to readonly again. I don't know where's my error.

Here's my jquery code:

$("[id^=code]").on('change',function(){
    var index = this.id.match(/\d+/)[0];
    var validate = $('#code'+index).val();

    if(validate != ''){
        $("#qty"+index).removeAttr('readonly');
        $("#price"+index).removeAttr('readonly');
    }        
});

$("[id^=code]").on('change',function(){
    var index = this.id.match(/\d+/)[0];
    var validate = $('#code'+index).val();

    if(validate == ''){
        $("#qty"+index).attr('readonly');
        $("#price"+index).attr('readonly');
    }        
});

And this is my table

for($i = 1; $i < 16; $i++){
    echo "<!-- ITEM {$i} -->";
    echo "<tr>";
    echo "<td>";
    echo "<select name='code[]' id='code{$i}' style='width:100'>";
    echo "<option value=''><label>--CHOOSE ITEMS--</label></option>";
    foreach($resultGetCode->result_array() as $list){
        echo "<option value='".$list['itemid']."'>".$list['itemcode']." --- ".$list['itemname']."</option>";  
    }
    echo "</select>";
    echo "</td>";
    //echo "<td><input type='text' name='item[]' class='k-textbox' id='item{$i}' value='' /></td>";
    echo "<td><input type='text' name='qty[]' id='qty{$i}' style='text-align: center' readonly='readonly' /></td>";
    echo "<td><input type='text' name='price[]' id='price{$i}' style='text-align: right;' onblur='' readonly='readonly' /></td>";
    echo "<td><input type='text' name='total[]' id='total{$i}' style='font-family: courier; text-align: right; background-color: lightgray; color: red' readonly='readonly' value='' /></td>";
    echo "<tr>";
}

Here's the fiddle: http://jsfiddle.net/rochellecanale/jnkc3/5/

Answer 1

Would be easier to help you if you create a fiddle, but try this

if(validate == ''){
     $("#qty"+index).prop('readonly', true);
     $("#price"+index).prop('readonly', true);
 }

Update . FIDDLE