php中已有数据自动带入表单

var userName        = '<?php if (isset($username)) echo $username?>';
var phoneNum        = '<?php if (isset($phonenum)) echo $phonenum?>';
var userEmail        = '<?php if (isset($useremail)) echo $useremail?>';
var companyName      = '<?php if (isset($companyname)) echo $companyname?>';
if (userName != '')        $('#userName').val(userName);
if (phoneNum != '')        $('#phoneNum').val(phoneNum);
if (userEmail != '')    $('#userEmail').val(userEmail);
if (companyName != '')    $('#companyName').val(companyName);