var str = ‘hello hcy’;str.indexOf(“a”) //-1 返回”a”在字符串中的开始下标str.lastIndexOf(“l”) //3 str.toUpperCase() //“HELLO HCY” 返回大写字符str.toLowerCase() //“hello hcy” 返回小写字符str.substr(start, end) //截取字符串var str1 = str.substr(1,3);//“ell” 含头含尾str.substring(start, end) //截取字符串var str2 = str.substring(1,3);//“el” 含头不含尾str.slice(start, end) //截取字符串var str3 = str.slice(1,3);//“el” 含头不含尾str.trim() //去掉首尾空格str.replace(regexp) //替换字符串str.replace(‘o’,‘ppp’); //hellppp hcystr.match() 匹配字符串str.search() 搜索字符串str.split() //字符串转换成数组str.split(’’); // [“h”, “e”, “l”, “l”, “o”, " “, “h”, “c”, “y”]