你好：

var?a=[{name:1,key:'a'},{name:2,key:'b'},{name:3,key:'a'},{name:3,key:'b'}];
		var?result?=?new?Array();
		for(var?index?in?a){
		?result[a[index].key]?=?new?Array();
		?result[a[index].key].push(a[index]);
		}
		console.log(result);

望采納！

var?b?=?{};
a.forEach(function?(obj)?{
????var?array?=?b[obj['key']]?||?[];
????array.push(obj);
????b[obj['key']]?=?array;
});
console.log(b.a.length);console.log(b.b.length);