01. 문자열 : 문자열 결합 / 템플릿 문자열

템플릿 문자열은 내장된 표현식을 허용하는 문자열 리터럴이다.

번호 기본값 메서드 리턴값 
{
    //01
    const str1 = "자바스크립트";
    const str2 = "제이쿼리";

    document.querySelector(".sample01_N1").innerHTML = "1";
    document.querySelector(".sample01_Q1").innerHTML = "자바스크립트, 제이쿼리";
    document.querySelector(".sample01_M1").innerHTML = "문자열(string) 결합";
    document.querySelector(".sample01_P1").innerHTML = str1 + str2;

    //02
    const num1 = 100;
    const num2 = 200;

    document.querySelector(".sample01_N2").innerHTML = "2";
    document.querySelector(".sample01_Q2").innerHTML = "100, 200";
    document.querySelector(".sample01_M2").innerHTML = "숫자(number) 결합";
    document.querySelector(".sample01_P2").innerHTML = num1 + num2;

    //03
    const text1 = "모던";
    const text2 = "자바스크립트";
    const text3 = "핵심";

    document.querySelector(".sample01_N3").innerHTML = "3";
    document.querySelector(".sample01_Q3").innerHTML = "모던, 자바스크립트, 핵심";
    document.querySelector(".sample01_M3").innerHTML = "문자열(string) 결합";
    document.querySelector(".sample01_P3").innerHTML = "나는 " + text1 + "(modern) " + text2 + "(javascript) " + text3 + "을 배우고 싶다.";

    //04
    document.querySelector(".sample01_N4").innerHTML = "4";
    document.querySelector(".sample01_Q4").innerHTML = "모던, 자바스크립트, 핵심";
    document.querySelector(".sample01_M4").innerHTML = "템플릿 문자열";
    document.querySelector(".sample01_P4").innerHTML = `나는 ${text1}(modern) ${text2}(javascript) ${text3}을 배우고 싶다.`;
}

02. toUpperCase() / toLowerCase()

toUpperCase()는 문자열을 대문자로 변경하고, toLowerCase()는 문자열을 소문자로 변경합니다.

번호 기본값 메서드 리턴값 
{
    const str1 = "javascript";
    const currentStr1 = str1.toUpperCase();
    
    document.querySelector(".sample02_N1").innerHTML = "1";
    document.querySelector(".sample02_Q1").innerHTML = "javascript";
    document.querySelector(".sample02_M1").innerHTML = "toUpperCase()";
    document.querySelector(".sample02_P1").innerHTML = currentStr1;
    
    const str2 = "JAVASCRIPT";
    const currentStr2 = str1.toLowerCase();
    
    document.querySelector(".sample02_N2").innerHTML = "2";
    document.querySelector(".sample02_Q2").innerHTML = "JAVASCRIPT";
    document.querySelector(".sample02_M2").innerHTML = "toLowerCase()";
    document.querySelector(".sample02_P2").innerHTML = currentStr2;    
}

03. trim() / trimStart() / trimEnd()

문자열의 앞/뒤 공백을 제거합니다.

번호 기본값 메서드 리턴값 
{
    const str1 = "      javascript      ";
    const currentStr1 = str1.trim();

    document.querySelector(".sample03_N1").innerHTML = "1";
    document.querySelector(".sample03_Q1").innerHTML = str1;
    document.querySelector(".sample03_M1").innerHTML = "trim()";
    document.querySelector(".sample03_P1").innerHTML = currentStr1;

    const str2 = "      javascript      ";
    const currentStr2 = str2.trimStart();

    document.querySelector(".sample03_N2").innerHTML = "2";
    document.querySelector(".sample03_Q2").innerHTML = str2;
    document.querySelector(".sample03_M2").innerHTML = "trimStart()";
    document.querySelector(".sample03_P2").innerHTML = currentStr2;

    const str3 = "      javascript      ";
    const currentStr3 = str3.trimEnd();

    document.querySelector(".sample03_N3").innerHTML = "3";
    document.querySelector(".sample03_Q3").innerHTML = str3;
    document.querySelector(".sample03_M3").innerHTML = "trimEnd()";
    document.querySelector(".sample03_P3").innerHTML = currentStr3;                   
}

04. slice() / substring() / substr()

문자열에서 원하는 값을 추출하여 문자열을 반환하는 메서드입니다.

"문자열".slice(시작위치)
"문자열".slice(시작위치, 끝나는위치)
//시작 위치의 값은 끝나는 위치 값보다 작아야 합니다.
//substring() 시작값이 끝나는 값보다 클 경우 두 값을 바꿔서 처리(에러 방지)
"문자열".substr(시작위치)
"문자열".substr(시작위치, 길이) 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.slice(0);  //javascript reference
    const currentStr2 = str1.slice(1);  //avascript reference
    const currentStr3 = str1.slice(2);  //vascript reference
    const currentStr4 = str1.slice(0, 1);  //j
    const currentStr5 = str1.slice(0, 2);  //ja
    const currentStr6 = str1.slice(0, 3);  //jav
    const currentStr7 = str1.slice(1, 2);  //a
    const currentStr8 = str1.slice(1, 3);  //av
    const currentStr9 = str1.slice(1, 4);  //avs
    const currentStr10 = str1.slice(-1);   //e
    const currentStr11 = str1.slice(-2);   //ce
    const currentStr12 = str1.slice(-3);   //nce
    const currentStr13 = str1.slice(-3, -1);   //nc
    const currentStr14 = str1.slice(-3, -2);   //n
    const currentStr15 = str1.slice(-3, -3);   //

    const currentStr16 = str1.slice(1, 4);  //ava 
    const currentStr17 = str1.slice(4, 1);  //'' 
    const currentStr18 = str1.substring(1, 4);  //ava 
    const currentStr19 = str1.substring(4, 1);  //ava 

    const currentStr20 = str1.substr(0);  //javascript reference
    const currentStr21 = str1.substr(1);  //avascript reference
    const currentStr22 = str1.substr(2);  //vascript reference
    const currentStr23 = str1.substr(0, 1);  //j
    const currentStr24 = str1.substr(0, 2);  //ja
    const currentStr25 = str1.substr(0, 3);  //jav
    const currentStr26 = str1.substr(1, 2);  //av
    const currentStr27 = str1.substr(1, 3);  //ava
    const currentStr28 = str1.substr(1, 4);  //avas
    const currentStr29 = str1.substr(-1);  //e
    const currentStr30 = str1.substr(-2);  //ce
    const currentStr31 = str1.substr(-3);  //nce
    const currentStr32 = str1.substr(-1, 1);  //e
    const currentStr33 = str1.substr(-2, 2);  //ce
    const currentStr34 = str1.substr(-3, 3);  //nce
}

05. split()

문자열에서 원하는 값을 추출 배열로 반환합니다.

"문자열".split(구분자);
"문자열".split(정규식 표현);
"문자열".split(구분자, 갯수); 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.split('');      // ['j','a','v','a','s','c','r','i','p','t','','r','e','f','e','r','e','n','c','e']
    const currentStr2 = str1.split(' ');     // ['javascript', 'reference']
    const currentStr3 = str1.split('', 1);   // ['j']
    const currentStr4 = str1.split('', 2);   // ['j', 'a']
    const currentStr5 = str1.split(' ', 1);  // ['javascript']
    const currentStr6 = str1.split(' ', 2);  // ['javascript', 'reference']
    const currentStr7 = str1.split('j');     // ['', 'avascript reference']
    const currentStr8 = str1.split('a');     // ['j', 'v', 'script reference']
    const currentStr9 = str1.split('e');     // ['javascript r', 'f', 'r', 'nc', '']

    const str2 = "java/script/refer/ence";
    const currentStr10 = str2.split('/');    // ['java', 'script', 'refer', 'ence']

    const str3 = "java&script&refer!ence";
    const currentStr11 = str3.split('!');       // ['java&script&refer', 'ence']
    const currentStr12 = str3.split('&');       // ['java', 'script', 'refer!ence']
    const currentStr13 = str3.split(/&|\!/);    // ['java', 'script', 'refer', 'ence']

    const str4 = "javascript reference";
    const currentStr14 = str4.split('').join();                 //j,a,v,a,s,c,r,i,p,t, ,r,e,f,e,r,e,n,c,e
    const currentStr15 = str4.split('').join('*');              //j*a*v*a*s*c*r*i*p*t* *r*e*f*e*r*e*n*c*e
    const currentStr16 = str4.split('').reverse().join();       //e,c,n,e,r,e,f,e,r, ,t,p,i,r,c,s,a,v,a,j
    const currentStr17 = str4.split('').reverse().join('/');    //e/c/n/e/r/e/f/e/r/ /t/p/i/r/c/s/a/v/a/j
}

06. replace() / replaceAll()

replace() 메서드는 문자열을 부분 문자ㄹ로 구분하고 배열로 반환합니다.

{
    const str1 = "javascript reference";
    const cirrentStr1 = str1.replace("javascript", "자바스크립트");     //자바스크립트 reference
    const cirrentStr2 = str1.replace("j", "J");                      //Javascript reference
    const cirrentStr3 = str1.replace("e", "E");                      //javascript rEference
    const cirrentStr4 = str1.replaceAll("e", "E");                   //javascript rEfErEncE
    const cirrentStr5 = str1.replace(/e/g, "E");                     //javascript rEfErEncE
    const cirrentStr6 = str1.replace(/e/gi, "E");                    //javascript rEfErEncE

    const str2 = "https://www.naver.com/img01.jpg";
    const cirrentStr7 = str2.replace("img01.jpg", "img02.jpg");  

    const str3 = "010-2000-1000";
    const cirrentStr8 = str3.replace("-", "");            //0102000-1000
    const cirrentStr9 = str3.replaceAll("-", "");         //01020001000
    const cirrentStr10 = str3.replace(/-/g, "");          //01020001000
    const cirrentStr11 = str3.replace(/-/g, " ");         //010 2000 1000
    const cirrentStr12 = str3.replace(/[1-9]/g, "*");     //0*0-*000-*000
}

07. concat()

concat() 메서드는 둘 이상의 문자열을 결합아여, 새로운 문자열을 반환합니다.

{
    const str1 = "javascript";
    const currentStr1 = str1.concat("reference");                       //javascriptreference
    const currentStr2 = str1.concat(" ", "reference");                  //javascript reference
    const currentStr3 = str1.concat(", ", "reference");                 //javascript, reference
    const currentStr4 = str1.concat(", ", "reference", ", ", "book");   //javascript, reference, book
    const currentStr5 = str1.concat(",", ["reference","book"]);         //javascript,reference,book
}

08. repeat()

repeat() 메서드는 문자열을 복사하여, 복사한 새로운 문자열을 반환합니다.

{
    const str1 = "javascript";
    const currentStr1 = str1.repeat(0);     //''
    const currentStr2 = str1.repeat(1);     //javascript
    const currentStr3 = str1.repeat(2);     //javascriptjavascript
}

09. padStart() / padEnd()

padStart/padEnd() 메서드는 주어진 길이에 맞게 앞/뒤 문자열을 채우고, 새로운 문자열을 반환합니다.

{
    const str1 = "456";
    const currnetStr1 = str1.padStart(1, "0");  //456
    const currnetStr2 = str1.padStart(2, "0");  //456
    const currnetStr3 = str1.padStart(3, "0");  //456
    const currnetStr4 = str1.padStart(4, "0");  //0456
    const currnetStr5 = str1.padStart(5, "0");  //00456
    const currnetStr6 = str1.padStart(6, "0");  //000456
    const currnetStr7 = str1.padStart(6, "1");      //111456
    const currnetStr8 = str1.padStart(6, "12");     //121456
    const currnetStr9 = str1.padStart(6, "123");    //123456
    const currnetStr10 = str1.padStart(6, "1234");  //123456
    const currnetStr11 = str1.padStart(6);          //   456

    const currnetStr12 = str1.padEnd(1, "0");       //456
    const currnetStr13 = str1.padEnd(2, "0");       //456
    const currnetStr14 = str1.padEnd(3, "0");       //456
    const currnetStr15 = str1.padEnd(4, "0");       //4560
    const currnetStr16 = str1.padEnd(5, "0");       //45600
    const currnetStr17 = str1.padEnd(6, "0");       //456000
    const currnetStr18 = str1.padEnd(6, "1");       //456111
    const currnetStr19 = str1.padEnd(6, "12");      //456121
    const currnetStr20 = str1.padEnd(6, "123");     //456123
    const currnetStr21 = str1.padEnd(6, "1234");    //456123
    const currnetStr22 = str1.padEnd(6);            //456___
}

10. indexOf()

문자열에서 특정 문자의 위치를 찾고, 숫자를 반환합니다.

"문자열".indexOf(검색값)
"문자열".indexOf(검색값, 위치값) 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.indexOf("javascript");        //0
    const currentStr2 = str1.indexOf("reference");         //11
    const currentStr3 = str1.indexOf("j");                 //0
    const currentStr4 = str1.indexOf("a");                 //1
    const currentStr5 = str1.indexOf("v");                 //2
    const currentStr6 = str1.indexOf("jquery");            //-1
    const currentStr7 = str1.indexOf("b");                 //-1
    const currentStr8 = str1.indexOf("javascript", 0);     //0
    const currentStr9 = str1.indexOf("javascript", 1);     //-1
    const currentStr10 = str1.indexOf("reference", 0);     //11
    const currentStr11 = str1.indexOf("reference", 1);     //11
    const currentStr12 = str1.indexOf("reference", 11);    //11
    const currentStr13 = str1.indexOf("reference", 12);    //-1

    const currentStr14 = str1.lastIndexOf("javascript");    //0
    const currentStr15 = str1.lastIndexOf("reference");     //11
    const currentStr16 = str1.lastIndexOf("j");             //0
    const currentStr17 = str1.lastIndexOf("a");             //3
    const currentStr18 = str1.lastIndexOf("v");             //2
    const currentStr19 = str1.lastIndexOf("jquery");        //-1
    const currentStr20 = str1.lastIndexOf("b");             //-1
    const currentStr21 = str1.lastIndexOf("javascript", 0);     //0
    const currentStr22 = str1.lastIndexOf("javascript", 1);     //0
    const currentStr23 = str1.lastIndexOf("reference", 0);      //-1
    const currentStr24 = str1.lastIndexOf("reference", 1);      //-1
    const currentStr25 = str1.lastIndexOf("reference", 11);     //11
    const currentStr26 = str1.lastIndexOf("reference", 12);     //11
}

11. includes()

includes() 메서드는 문자열 포함 여부를 검색하여, 불린(true, false)을 반환합니다.

"문자열".includes(검색값)
"문자열".includes(검색값, 시작값) 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.includes("javascript");     //true
    const currentStr2 = str1.includes("j");              //true
    const currentStr3 = str1.includes("b");              //false
    const currentStr4 = str1.includes("reference");      //true
    const currentStr5 = str1.includes("reference", 1);   //true
    const currentStr6 = str1.includes("reference", 11);  //true
    const currentStr7 = str1.includes("reference", 12);  //false
}

12. search()

search() 메서드는 문자열(정규식)을 검색하고 위치값(숫자)를 반환홥니다.

"문자열".search("검색값");
"문자열".search(정규식 표현); 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.search("javascript");        //0
    const currentStr2 = str1.search("reference");         //11
    const currentStr3 = str1.search("j");                 //0
    const currentStr4 = str1.search("a");                 //1
    const currentStr5 = str1.search("v");                 //2
    const currentStr6 = str1.search("jquery");            //-1
    const currentStr7 = str1.search("b");                 //-1
    const currentStr8 = str1.search(/[a-z]/g);            //0
}

13. match()

match() 메서드는 문자열(정규식)을 검색하고 문자값(배열)을 반환합니다.

"문자열".match(검색값)
"문자열".match(정규식 표현) 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.match("javascript");       //javascript  
    const currentStr2 = str1.match("reference");        //reference  
    const currentStr3 = str1.match("r");                //r
    const currentStr4 = str1.match(/reference/);        //reference
    const currentStr5 = str1.match(/Reference/);        //null
    const currentStr6 = str1.match(/Reference/i);       //reference
    const currentStr7 = str1.match(/r/g);               //['r', 'r', 'r']
    const currentStr8 = str1.match(/e/g);               //['e', 'e', 'e', 'e']
}

14. charAt()

charAt() 메서드는 지정한 숫자(index)의 단일 문자 값을 반환합니다. charCodeAt()메서드는 지정한 숫자의 유니코드 값을 반환합니다.

"문자열".charAt(숫자) "문자열".charCodeAt(숫자) 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.charAt();          //j  
    const currentStr2 = str1.charAt("0");       //j  
    const currentStr3 = str1.charAt("1");       //a  
    const currentStr4 = str1.charAt("2");       //v 

    const currentStr5 = str1.charCodeAt();      //106
    const currentStr6 = str1.charCodeAt("0");   //106
    const currentStr7 = str1.charCodeAt("1");   //97
    const currentStr8 = str1.charCodeAt("2");   //118
}

15. startsWidth() / endsWith()

startsWidth() 메서드는 시작하는 문자열에서 문자열을 검색하여 불린(true, false)을 반환합니다.
endWidth() 메서드는 끝나는 문자열에서 문자열을 검색하여 불린(true, false)을 반환합니다.

"문자열".startsWidth(검색 문자열)
"문자열".startsWidth(검색 문자열, 위치값)
"문자열".endsWith(검색 문자열)
"문자열".endsWith(검색 문자열, 시작 위치값) 
{
    const str1 = "javascript reference";
    const currentStr1 = str1.startsWith('javascript');      //true
    const currentStr2 = str1.startsWith('j');               //true
    const currentStr3 = str1.startsWith('java');            //true
    const currentStr4 = str1.startsWith('reference');       //fasle
    const currentStr5 = str1.startsWith();                  //fasle
    const currentStr6 = str1.startsWith('');                //true
    const currentStr7 = str1.startsWith('reference', 7);    //fasle
    const currentStr8 = str1.startsWith('reference', 11);   //true

    const currentStr9 = str1.endsWith('reference');        //true
    const currentStr10 = str1.endsWith('e');               //true
    const currentStr11 = str1.endsWith('refer');           //fasle
    const currentStr12 = str1.endsWith('javascript');      //fasle
    const currentStr13 = str1.endsWith();                  //fasle
    const currentStr14 = str1.endsWith('');                //true
    const currentStr15 = str1.endsWith('reference', 7);    //fasle
    const currentStr16 = str1.endsWith('reference', 20);   //true
}