标签：ar sp bs ef nbsp br type js false
var bbb1 = typeof str== ‘undefined‘; //true
var bbb2 = typeof str== undefined; //false
var bbb3 = str== undefined; //true
var bbb4 = str== ‘undefined‘; //undefined
标签：ar sp bs ef nbsp br type js false
原文地址：http://www.cnblogs.com/paste/p/4167427.html
