Html: for the Select Multiple parameter, only one value is sent, but .val () returns an array of two values

Question

When rendering a page, the val() parameter for multiple selection is set to a single value. For example, $("#my_select_box").val(1); The user then selects an additional value in the multiple selection field.

When a form is submitted, only the newly selected value is submitted, not the previously set value. If, during debugging in Firefox, the .val() function returns an array of two values ​​(both the previous and the new). Why is this happening?

Answer 1

If you are programming in PHP, the problem is there. When using multi-selective inputs, PHP requires an empty pair of brackets after the input name. For example:

 <select name="select[]" multiple="multiple"> 

not just

 <select name="select" multiple="multiple"> 

If you don’t or don’t (perhaps you don’t have access to the basic HTML), you can also write POST data as follows:

 $data_from_post = file_get_contents("php://input"); var_dump($data_from_post); 

And you will see a line that you can use:

 select=one&select=two&select=three&button=submit 

Answer 2

Well, without code, we cannot be sure. But when you need to pass a few parameters, you must specify a name that introduces the brackets []. Ex. "name []" so that the server knows that there are actually two values.

Answer 3

It's hard to say what to do without code.

However, if you want both the option you checked selected and the other that was selected, you can access them as follows:

option[selected="selected"] for the one you installed

and

option:selected for the selection selected by the user

So something like this ...

 $('#submit').click(function(){ var s = $('#my_select_box option[selected="selected"]').val(); var t = $('#my_select_box option:selected').val(); alert("Set: " + s + ", Chosen: " + t); }); 

Example: http://jsfiddle.net/jasongennaro/pZesG/1/