padStart() / padEnd()

padStart() / padEnd()란?

padStart()/padEnd()는 주어진 길이에 맞게 앞/뒤 문자열을 채우고, 새로운 문자열을 반환해주는 메서드 입니다.

const str1 = "cat"
const currentStr1 = str1.padStart(1,"0"); //cat
const currentStr2 = str1.padStart(3,"0"); //cat
const currentStr3 = str1.padStart(4,"0"); //0cat
const currentStr4 = str1.padStart(6,"0"); //000cat

const currentStr4 = str1.padEnd(3,"0"); //cat
const currentStr5 = str1.padEnd(4,"0"); //cat0
const currentStr6 = str1.padEnd(6,"0"); //cat000

"문자열",padStart(길이)
"문자열",padStart(길이,문자열)

 

    const str1 = "456";
    const currentStr1 = str1.padStart(1,"0");       //456
    const currentStr2 = str1.padStart(2,"0");       //456
    const currentStr3 = str1.padStart(3,"0");       //456
    const currentStr4 = str1.padStart(4,"0");       //0456
    const currentStr5 = str1.padStart(5,"0");       //00456
    const currentStr6 = str1.padStart(6,"0");       //000456
    const currentStr7 = str1.padStart(6,"1");       //111456
    const currentStr8 = str1.padStart(6,"12");     //121456
    const currentStr9 = str1.padStart(6,"123");     //123456
    const currentStr10 = str1.padStart(6,"1234"); //123456
    const currentStr11 = str1.padStart(6);           //___456 //문자열이 없으면 길이만큼 앞에 공백처리가 된다.
    
    const currentStr12 = str1.padEnd(1,"0");       //456
    const currentStr13 = str1.padEnd(2,"0");       //456
    const currentStr14 = str1.padEnd(3,"0");       //456
    const currentStr15 = str1.padEnd(4,"0");       //4560
    const currentStr16 = str1.padEnd(5,"0");       //45600
    const currentStr17 = str1.padEnd(6,"0");       //456000
    const currentStr18 = str1.padEnd(6,"1");       //456111
    const currentStr19 = str1.padEnd(6,"12");        //456121
    const currentStr20 = str1.padEnd(6,"123");      //456123
    const currentStr21 = str1.padEnd(6,"1234");    //456123
    const currentStr22 = str1.padEnd(6);              //456___