NodeJS-创建空数组会导致数组中包含大量空值 [英] NodeJS - Creating empty array results in array with a lot of nulls
问题描述
我正在使用socket.io创建Node.js聊天。
问题是当我看到<$ c $的 console.log
时$ c> history 我看到一个带有很多空值的数组,最后我的历史记录条目
[null,null,null ... [ {用户名:'Nobody Example',消息:'231',日期:'03 / 21/2013 14:23:58'}]]
I am creating a Node.js chat using socket.io
The problem is that when I see the console.log
of history
I see an array with A LOT of nulls and at the end my history entries
[null,null,null......[ { username: 'Nobody Example', message: '231', date: '03/21/2013 14:23:58' } ]]
这些空值如何出现在数组中?
这是我的代码的一部分。
How come these nulls are in the array?
Here is a part of my code.
var history = [];
io.sockets.on('connection', function (socket) {
socket.on('send', function (message) {
var date = time();
io.sockets.in(socket.room).emit('message', socket.username, message, date);
history[socket.room].push({ username: socket.username, message: message, date: date });
console.log(history);
});
socket.on('joinroom', function (room, username) {
socket.room = room;
socket.join(room);
if ( typeof history[room] === 'undefined' )
history[room] = [];
});
});
编辑以获取更多详细信息:
Edit for more details:
问题是在为每个房间创建空数组时的'joinroom'事件中。
这是我进行的一些测试:
The problem is in the 'joinroom' event when creating the empty array for each room.
Here are few tests that I've made:
socket.on('joinroom', function (room, username) {
socket.room = room;
socket.join(room);
console.log(typeof history[room] == 'undefined');
history[room] = [];
console.log(typeof history[room] == 'undefined');
console.log(JSON.stringify(history));
});
控制台日志:
true
false
[null,null,null,null,..................,null,[]]
推荐答案
如果您有一个空数组,并使用大量数字(例如您的房间ID)对其进行索引,则该数字之前的所有插槽充满 undefined
(在JSON中转换为 null
)。
If you have an empty array and index it with a large number (like your room id's), all slots in the array before that number are filled with undefined
(which translates to null
in JSON).
因此,请尝试使历史成为对象:
So try making history an object instead:
var history = {};
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