//计算字符串长度
function strlen(str) {
	var len = 0;
	for (var i = 0; i < str.length; i++) {
		if (str.charCodeAt(i) > 255) len += 2; else len ++;
	}
	return len;
}

//去掉字符串首尾的空格
function trim(str) {
	return str.replace(/^\s*/g,"").replace(/\s*$/g,"");
}

//电子邮件的正则测试
function checkEmail(str) {
	var pattern = /^[A-Za-z0-9_/.]+@\w+(\.[a-zA-Z]{1,4})(?!\1)(\.[a-zA-Z]{1,2})?$/;
	return pattern.test(str);
}