/**
 * 是否是正确的 email 格式
 * @param emailStr 要判断的 email
 * @return 如果正确返回true，否则返回false
 */
function isEmail(emailStr) {
	if (emailStr.length == 0) {
		return false;
	}
	// 域名检测默认打开
	var checkTLD = 1;
	var knownDomsPat = /^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
	var emailPat = /^(.+)@(.+)$/;
	var specialChars = "\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
	var validChars = "\[^\\s" + specialChars + "\]";
	var quotedUser = "(\"[^\"]*\")";
	var ipDomainPat = /^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
	var atom = validChars + '+';
	var word = "(" + atom + "|" + quotedUser + ")";
	var userPat = new RegExp("^" + word + "(\\." + word + ")*$");
	var domainPat = new RegExp("^" + atom + "(\\." + atom + ")*$");
	var matchArray = emailStr.match(emailPat);
	if (matchArray == null) {
		return false;
	}
	var user = matchArray[1];
	var domain = matchArray[2];
	for (i = 0; i < user.length; i++) {
		if (user.charCodeAt(i) > 127) {
			return false;
		}
	}
	for (i = 0; i < domain.length; i++) {
		if (domain.charCodeAt(i) > 127) {
			return false;
		}
	}
	if (user.match(userPat) == null) {
		return false;
	}
	var IPArray = domain.match(ipDomainPat);
	if (IPArray != null) {
		for ( var i = 1; i <= 4; i++) {
			if (IPArray[i] > 255) {
				return false;
			}
		}
		return true;
	}
	var atomPat = new RegExp("^" + atom + "$");
	var domArr = domain.split(".");
	var len = domArr.length;
	for (i = 0; i < len; i++) {
		if (domArr[i].search(atomPat) == -1) {
			return false;
		}
	}
	if (checkTLD && domArr[domArr.length - 1].length != 2
			&& domArr[domArr.length - 1].search(knownDomsPat) == -1) {
		return false;
	}
	if (len < 2) {
		return false;
	}
	return true;
}