Nodejs基础系列-07- javascript 字符串处理

电玩女神 2023-07-03 03:26 25阅读 0赞

//字符串处理
    //01-常用转义
    //单引号转义\'
    let s1="I\'am like footbool!"
    console.log(s1); //I'am like footbool!
    //双引号 \"
    let s2="I \"think\" I \"am\" "
    console.log(s2) ;//I "think" I "am"
    //反斜杠 \\
    let s3="one\\two\\three"
    console.log(s3);//one\two\three
    //换行符 \n
    let s4="I am \nI happy "
    console.log(s4);
    //I am
    //I happy
    //制表符/\t
    let s5="one\ttwo\tthree"
    console.log(s5);//one  two three
    
    //02-合并字符串 concat
    let word1="Today ";
    let word2="is ";
    let word3="Sunday";
    let wordconstr1=word1+word2+word3;
    let wordconstr2=word1.concat(word2,word3);
    console.log(wordconstr1);//Today is Sunday
    console.log(wordconstr2);//Today is Sunday
    
    
    //03-在字符串中搜索字符串 indexOf (第一次出现的位置）
    let myStr="In the past five years, I\'am found a good  five path.";
    if(myStr.indexOf("five")!=-1){
        console.log(myStr.indexOf("five"))//12
        console.log(myStr);//In the past five years, I'am found a good  five path.
    }
    
    //lastIndexOf  (最后一次出现的位置）
    if(myStr.lastIndexOf("five")!=-1){
        console.log(myStr.lastIndexOf("five"))//43
     }
    
    
    //04-字符串分割成数组 split
    let strdtr="2020:02:01";
    let arr_dtr=strdtr.split(":");
    console.log(arr_dtr[0]);//2020
    console.log(arr_dtr[1]);//02
    console.log(arr_dtr[2]);//01
    
    //05-charAt(index)返回指定索引出的字符
    console.log(myStr.charAt(10)); //t   注意从0开始。
    
    //06-charCodeAt(index)返回指定索引处字符的unicode值
    console.log(myStr.charCodeAt(10)) //116
    
    //07-replace(subString/regex,replacementString)
    //搜索字符串或正则表达式匹配，并用新的字符串替换配置的字符串(注意：仅替换第一次出现的）
    let myStr_rp= myStr.replace("five","six");
    console.log(myStr_rp);//In the past six years, I'am found a good  five path.
    
    
    //把字符串中所有"five" 替换成了"six"
    while (myStr.indexOf("five")!=-1){
        myStr=myStr.replace("five","six");
    }
    console.log(myStr);//In the past six years, I'am found a good  six path.
    
    
    //08-返回 slice(start,end)返回start和end（不含）之间的一段新字符串
    let myStr_btw="long long ago there was a king";
    console.log(myStr_btw.slice(1,12));//ong long ag
    
    //09-substr(start,length) 从指定位置开始按照指定长度提取字符串
    console.log(myStr_btw.substr(0,13));//long long ago
    
    //10-substring(from ,to) 返回字符索引from与to（不含）之间的子串,与slice结果一样
    console.log(myStr_btw.substring(1,12));//ong long ag
    
    //11-大小写转换 toUpperCase()转大写；  toLowerCase()转小写
    console.log(myStr_btw.toUpperCase());//LONG LONG AGO THERE WAS A KING