无法在setInterval中读取属性

Question

在node.js上，我得到一个错误：

TypeError: Cannot read property 'talk_duration' of undefined

出发地：setTimeout(this.hangup, this.data.talk_duration * 1000); in the setInterval。

但是，在setInterval之外，我有一个工作良好的console.log(this.data.talk_duration);。

this.outcomeAnswer = function () {

    console.log(this.data.talk_duration); //this work

    num = 0;

    db.run("INSERT INTO in_queue (action_id, state) VALUES ('" + this.data.action_id + "', 'InQueue')", function (error) {
        queueCheckLoop = setInterval(function () {

            num++;

            if (num == 5) {
                clearInterval(queueCheckLoop);
            }

            db.each("SELECT count(*) as total FROM agent_queue WHERE state = 'Ready'", function (err, row) {
                if (row.total > 0) {
                    clearInterval(queueCheckLoop);
                    setTimeout(this.hangup, this.data.talk_duration * 1000);
                }
            });
        }, 1000);
    });
}

Answer 1

您需要正确地记住this作为您的oucomeAnswer函数的顶部一行，例如：var that=this;

然后在不同作用域的函数中使用that.data.talk_duration。