Question

I want to show a parameter value when a user mouseover it. I want to do it with jquery. My function is returning an undefined value.

<script type="text/javascript">
$(function showinfo(id, a,b){
    $('div').mouseover(function(){
        var html= '<div>'+ a +'</div> <div>'+b+'</div>';
        $('body').append(html)
    })
})
</script>

HTML:

<div onmouseover="showinfo(this, '50','60')">show info</div>

Answer 1

I would suggest to do it slightly differently:

<div id="container">
    <div id="showInfo" >show info</div>
</div>

And jQuery:

$(document).ready(function() {
  $("#showInfo").mouseover(function() {
    showInfo($(this).attr("id"), '50', '60');
  });
});

function showInfo(id, a, b) {
  var html = '<div>'+a+'</div><div>'+b+'</div>';
  $("#container").append(html);
}

You can also have a look on hover function of jQuery.
jsFiddle here: http://jsfiddle.net/KvMuD/