js array 중복제거

• ES6
  • Set (가장 빠름)
    • [...new Set(arr)]
    • Array.from( new Set(arr) )
  • filter
    • arr.filter( (item,idx)=>arr.indexOf(item) === idx )
  • reduce
    • arr.reduce( (acc,curr)=>acc.includes(curr)? acc : [...acc,curr], [] )

https://dongmin-jang.medium.com/javascript-array-%EC%A4%91%EB%B3%B5-%EC%A0%9C%EA%B1%B0%ED%95%98%EB%8A%94-%EB%B0%A9%EB%B2%95-es6-b5b9075361f9

•  ES 6사용못할때
  • reduce, indexOf사용

    • arr.reduce(function(acc,curr,index){
          acc.indexOf(curr) > -1 ? acc : acc.push(curr);
          return acc;
      },[]);

  • filter, indexOf사용

    • arr.filter(function(a, i, self){
      	return self.indexOf(a) === i;
      });