Try this
function validate()
{
var n=document.getElementById("name").value;
var q=document.getElementById("quantity").value;
var p=document.getElementById("price").value;
var na=/^[a-z ]*$/;
var no=/^[0-9 ]*$/;
if (!na.test(n))
{
alert("Please enter valid name.");
return false;
}
if(!no.test(q) || !no.test(p))
{
alert("Please enter valid quantity & price.");
return false;
}
}