单击提交按钮后如何识别特定文本字段中值的变化

Question

I want to update marks of a particular student in particular subject out of eight subjects. My question is how to identify that a particular text box value has been changed after clicking submit button, then the updation task is forwarded to the update.php. Please give me your valuable answer. Thanks in advance.

Answer 1

Since your button click event is occured on client side, you can identify it by client side scripting.

 <script lang='javascript'>
 $(document).ready(function(){
    $('#button_id').click(function(){
             /* Do whatever you want to do right here*/
    });
 });
 </script>

For identifying the change on text box after clicking submit button, first change the input type from submit to button as as soon as you click submit, it redirects the page.

<input type='button' onClick='your_function()' id='btn_submit' name='btn_submit' />
<input type='text' id='text_box' name='text_box' onchange='$('#flag_value_changes').val('1')' />
<input type='hidden' id='flag_value_changes' name='flag_value_changes' />
<script lang='javascript'>
function your_function()
{
         flag_value_changes = $('#flag_value_changes').val();
         if(flag_value_changes == 1)
            alert('Value has been changed');
         else
            alert('Value has not been changed');
}
</script>

Answer 2

the scripting language can help you in this situation.use javascript for the event of the submit button click. do whatever you needed in that event..happy coding :)

Answer 3

As stated by hsuk. You can do it on the client side using javascript.
I've provided an example using textarea and no inline javascript.

HTML

<div>
  <textarea id= "math">Math</textarea>
  <textarea id= "english">English</textarea>
  <textarea id= "french">French</textarea>
  <textarea id= "spanish">Spanish</textarea>
  <input type="submit" value="submit"/>
</div>

And the following javascript(Using Jquery)

$(document).ready(function(){
    var initialValues = [];
    var i = 0;
   //Gets values on load
    $("div textarea").each(function(){
        initialValues[i] = this.id+" had "+$(this).val(); 
        i++;
    });

   //Checks values on click
    $("input").click(function(){
    i = 0;
    $("div textarea").each(function(){
        value = initialValues[i].split(" ");
        if($(this).val() != value[2]){
            alert(value[0] + " was Changed.");   
        }
        i++;
        });
    });
});

DEMO