数组去重

indexOf

        let arr = [1,2,3,4,5,6,7,1,2,3]
        quchong = (array) =>{
            let result = []
            for(let i = 0 ; i < array.length; i ++){
                if(result.indexOf(array[i]) === -1 ){
                    result.push(array[i])
                }
            }
            return result
        }
        console.log(quchong(arr))//[1,2,3,4,5,6,7]

Set

        let arr = [1,2,3,4,5,6,7,1,2,3]
        quchong = (array) =>{
            return [...new Set(array)]
        }
        console.log(quchong(arr))

数组排序

一些常考题