get all the input value and make an addition

Answer 1

Try this:

var $inputs = $('.liste_couleur_qty li input');
$inputs.keyup(function() {
   var result = 0;
   $inputs.each(function(){
     result += parseInt(this.value, 10);
   });
   $('#qtyvalue').html(result);    
});

This would need to be in a document ready handler or in a script block after the elements in question (many people put their scripts at the end of the body).

In your code, input.onkeyup = ... wouldn't work because there is no variable input (it doesn't automatically pick up all input elements), and also using someElement.onkeyup = only lets you attach a handler to one element at a time. Use jQuery to bind the keyup handler instead. Also, to use the total at the end just use result, using result.value wouldn't work.

Answer 2

What you want is this:

$(document).ready(function() { //wrap in a document.ready event handler
    $('input').on('keyup', function() { //bind using jQuery
        var result = 0;
        $('.liste_couleur_qty li input').each(function() {
            result += parseInt(this.value, 10);
        });
        $('div#qtyvalue').text(result); //result.value doesn't exist, use result.
    });
});​

Here's a demo: http://jsfiddle.net/jeRdA/

UDPATE:

To allow for users changing the value of any of the inputs to ''(e.g., blank, or empty) or a non-numeric value, modify the line:

result += parseInt(this.value, 10);

to:

result += parseFloat(this.value, 10) || 0;

Updated fiddle: http://jsfiddle.net/jeRdA/3/