办法一:应用 reduce,includes
1. 定义数组
let numArr = ['1','9','9','7','0','4','1','2','2','4','0']
2. 封装一个去重办法 remove()
function remove(arr) {return arr.reduce((newarr,cur) => {if(newarr.includes(cur) === false) newarr.push(cur)
return newarr
},[])
}
3. 执行去重办法 remove(numArr)
4. 输入后果 ['1','9','7','0','4','2']