JS数値を文字列で連結させる

function dateFormat(date) {
var y = date.getFullYear();
var m = date.getMonth() + 1;
var d = date.getDate();
var w = date.getDay();
if (m < 10) { m = '0' + m; } if (d < 10) { d = '0' + d; } return ""+ y + m + d; }