如何在jQuery中保留keyup事件的第一个原始值

Question

Here is my fiddle: http://jsfiddle.net/dQ6vZ/22/

I have a case where I have repeating elements with some numeric values.

<div class="chars">
    <textarea></textarea>
    <span class="myVal">5</span>
    <span class="pres"> - preserved: 5</span>
</div>

<div class="chars">
    <textarea></textarea>
    <span class="myVal">10</span>
    <span class="pres"> - preserved: 10</span>
</div>

On keyup event (when typing text) I am supposed to preserve the very first original value from span element with class myVal but update the value in the same element as I type.

So if the original value was 5, I need to keep 5 while I replace the value visible to the user with a new value.

My beginning looks something like this:

var new_value = 0;

$( ".chars" ).keyup(function() {

    var preserved_increment = parseInt($(this).find(".myVal").text());

    var text_length = parseInt($(this).find("textarea").val().length);

    new_value = text_length + preserved_increment;

    $(this).find(".myVal").text( new_value );
    $(this).find(".pres").text( " - not preserved: " + preserved_increment );
});

Answer 1

Use the data function provided by jQuery for this task.

I have updated your code to preserve the original value inside the text area. jsfiddle

To access the original value, simply call:

    var originalValue = $(this).find(".myVal").data("original")

Answer 2

use data-* attributes, and then use jQuery's .data method to get the value

HTML

<div class="chars">
    <textarea></textarea>
    <span class="myVal" data-preserved="5">5</span>
    <span class="pres"> - preserved: 5</span>
</div>

JS

var preserved_increment = parseInt($(this).find(".myVal").data("preserved"));

JSFiddle