Hi Djole,
In HTML the ID has to be unique, and you can have multiple save buttons on a form, so they all have to have a unique id.
Fortunately there are other selectors you can use;
So, as you know, the # means "match id". As in
$("#save_btn")
this will match to the item with id="save_btn"
You can also match on "function". All save buttons have an attribute
data-do="save"
The selector for this is
$("[data-do=save]")
Use this if you want your code to apply to _all_ the save buttons on the form.
Another approach is to add a CSS class to the button - you don't have to actually create a class, just assign a class to the button. Then only the specific buttons with your assigned class will be selected when you use a selector like this;
$(".someclass")
remember css is case sensitive though...
Selectors are an enormously powerful tool when it comes to writing JavaScript - you can read up on them on the jQuery site if you like.
Cheers
Bruce