JavaScript/jQuery
$("#entersomething").keyup(function(e){
var code = e.key; // recommended to use e.key, it's normalized across devices and languages
if(code==="Enter") e.preventDefault();
if(code===" " || code==="Enter" || code===","|| code===";"){
$("#displaysomething").html($(this).val());
} // missing closing if brace
});
HTML
<input id="entersomething" type="text" /> <!-- put a type attribute in -->
<div id="displaysomething"></div>