Can'；t在Node.js中的Redis中设置键

我正在尝试在Node.js中使用Redis。我做错了什么。。。我的头脑绕不过去

var redis = require("redis"), client = redis.createClient();

client.on("error", function (err) {
    console.log("error event - " + client.host + ":" + client.port + " - " + err);
});

/* first attempt */
console.log('first attempt');

var before = client.get("test");
console.log(before);

if(client.exists("test")) { 
    console.log("The value exists");
} else {
    console.log("The value doesn't exists");
    client.set("test","koen");
}

var after = client.get("test");
console.log(after);

/* second attempt */
console.log('--------------');
console.log('second attempt');

var before = client.get("test");
console.log(before);

if(client.exists("test")) { 
    console.log("The value exists");
} else {
    console.log("The value doesn't exists");
    client.set("test","koen");
}

var after = client.get("test");
console.log(after);

我无法设置任何键。。。控制台中显示以下内容：

first attempt
false
The value doesn't exists
false
--------------
second attempt
false
The value doesn't exists
false

---

client.set（）

不同步。您需要提供一个回调作为最后一个参数，此时您的键将被设置。

下面是一个如何设置和获取“test”的示例：

请记住，所有调用都必须是异步的

client.set("test", "koen", function (err, res) {
  console.log("set: ", res)

  client.get("test", function (err, res) {
    console.log("get: ", res);
  });

});