1.charAt()查找并返回指定位置的字符varstr="abcdefg";vars=str.charAt(5);//下标为5的字符console.log(s);//f2.charCodeAt()查找并返回指定位置字符的unicdoe码varstr="abcdefg";vars=str.charCodeAt(5);//下标为5的字符的unicdoe编码console.log(s);//1023.concat()connectionstringvarstr="abc";varstr1=str.concat("a","b","c","dsdafsdafsad");console.log(str1);//abcabcdsdafsdafsad4.slice()字符串截取varstr="abcdefghijklm";varstr1=str.slice(1,5);console.log(str1);//bcde5.split()把字符串转成数组varstr="abc?de?fg"varstr1=str.split("")varstr2=str.split("?")console.log(str);//abcdefgconsole.log(str1)//["a","b","c","?","d","e","?","f","g"]控制台.log(str2)//["abc","de","fg"]6.substring()字符串截取varstr="abcdefghijklm";varstr1=str.substring(1,9);//来自下标1到下标9，不包括下标9那一项varstr2=str.substring(9,1);console.log(str1);//bcdefghiconsole.log(str2);//bcdefghi7.substr()字符串截取varstr="abcdefghijklm";varstr1=str.substr(2,6);//从下标2截取6位console.log(str1);//cdefgh8.indexOf()遍历字符串寻找包含第一个参数的字符串，如果包含第一个数字的下标，则停止查找，如果不返回-1，第二个参数表示从这个下标开始查找。varstr="abcdefabcjklm";vara=str.indexOf("abc")varb=str.indexOf("abc",1);console.log(a);//0console.log(b);//69.toUpperCase转大写varstr="aAbBcCdD";console.log(str.toUpperCase());//AABBCCDD10.toLowerCase转小写varstr="aAbBcCdD";console.log(str.toLowerCase());//aabbccdd11.replace()替换字符串只能匹配一次varstr="Theweatheraregoodeverydaytoday";varstr1=str.replace("Everyday","**");console.log(str1);//今天**每天天气都很好12.match()查找字符串varstr="今天天气很好";varresult=str.match("everyday");console.log(result);//["每天",index:1,input:"今天天气好",groups:undefined]13.search()搜索字符串返回下标varstr="今天天气每天都好";varresult=str.search("everyday");console.log(result);//114.startsWith()判断一个字符串是否以另一个字符串开头varstr="helloworld";varresult=str.startsWith("he");console.log(result)//true//当有两个参数时，第二个表示起始位数。varresult=str.startsWith("他",1);console.log(result)//flase15.endsWith()判断一个字符串是否以另一个字符串结尾varstr="helloworld";//检查结束varresult=str.endsWith("world");console.log(result);//true//检测指定位置是否以指定字符结尾varresult1=str.endsWith("wo",8);console.log(result1)//true16.includes检测是否包含指定字符串varstr="helloworld";varresult=str.includes("o");console.log(result);//truevarresult1=str.includes("o",8);console.log(result1);//false17.repeat重复字符串varstr="haha"varstr1=str.repeat(3);console.log(str1)//哈哈哈哈哈
