javascript 数组处理，相同的放一起求大佬指点！

Question

假设有一个数组是这样[{eid:cat,name:aa},{eid:cat,name:bb},{eid:dog,name:cc},{eid:cat,name:dd},{eid:pig,name:ee},{eid:cat,name:ff},{eid:dog,name:gg}]我想要对数组做处理，将相同的eid放在一起变成[{eid:cat,name:aa},{eid:cat,name:bb},{eid:cat,name:dd},{eid:cat,name:ff},{eid:dog,name:cc},{eid:dog,name:gg},{eid:pig,name:ee}]这有办法实现吗?

Answer 1

vardata=[
{eid:'cat',name:'aa'},
{eid:'cat',name:'bb'},
{eid:'dog',name:'cc'},
{eid:'cat',name:'dd'},
{eid:'pig',name:'ee'},
{eid:'cat',name:'ff'},
{eid:'dog',name:'gg'}
]
functiontrans(data){
letcache={}//cache存储的键是eid，值是这个eid在indices数组中的下标
letindices=[]//数组中的每一个值是一个数组，数组中的每一个元素是原数组中相同eid的下标
data.forEach((item,i)=>{
leteid=item.eid
letindex=cache[eid]
if(index!==undefined){
indices[index].push(i)
}else{
cache[eid]=indices.length
indices.push([i])
}
})
/**
*此时，cache：{cat:0,dog:1,pig:2}
*indices:[[0,1,3,5],[2,6],[4]]
*indices中的第1项是eid为cat的数组下标
*indices中的第2项是eid为dog的数组下标
*indices中的第3项是eid为pig的数组下标
*/
letresult=[]
indices.forEach(item=>{
item.forEach(index=>{
result.push(data[index])//依次把index对应的元素data[index]添加进去即可
})
})
returnresult
}
letresult=trans(data)
console.log(result)
你的问题里面有个不明确的地方，比如下面这个例子：
vardata=[
{eid:'dog',name:'aa'},
{eid:'cat',name:'bb'},
{eid:'dog',name:'cc'}
]
你是想输出1：
[
{eid:'dog',name:'aa'},
{eid:'dog',name:'cc'},
{eid:'cat',name:'bb'}
]
还是想输出2：
[
{eid:'cat',name:'bb'},
{eid:'dog',name:'aa'},
{eid:'dog',name:'cc'}
]
输出1是按照出现的先后顺序排列的，输出2是按照字母序排列的，我给的是输出1的函数，如果想要输出2的结果，可以参考楼上。