{
let obj = {}
return arr.reduce((total,item) => {
let val = item[key];
if (!obj[val]) {
total.push(item)
obj[val] = val
}
return total;
},[])
}示例：
{
let obj = {}
return arr.reduce((total,item) => {
let val = item[key];
if (!obj[val]) {
total.push(item)
obj[val] = val
}
return total;
},[])
}示例：
