[nerv_]

GuardCat, http://es5.javascript.ru/x15.4.html#x15.4.4.21

<input type='checkbox' name='chec' id='chec' value='1000'>
<input type='checkbox' name='chec'  value='100'>
<input type='checkbox' name='chec' value='10'>
<input type='checkbox' name='chec' value='1'>

<input type = "button" id = "show" value = "show me">


<script>
    function getCheckboxesValues( name ) {
        return Array.prototype.reduce.call( document.getElementsByName( name ), function( sum, input ) {
            return sum += input.checked ? input.value : '';
        }, '' );
    }
  
  document.getElementById( "show" ).onclick = function() {
    alert( getCheckboxesValues( "chec" ) )
  }
</script>