另一个setInterval＆amp;这不起作用

Question

我在JavaScript中遇到this和setInterval的问题。我在这里阅读了几个解决方案，但无法让它们为我工作。这是我的代码：

var timer_func = function(){
    var that = this;
    var inspect = function(clusters){

        var clength = "";

        for(var i = 0; i < that.clusters.length; i++){   //---> undefined that.clusters.length
            clength += that.clusters[i].processes.length + ",";
        }

        console.log(clength);
    }

    var inspector = setInterval(inspect, 1000);
};
//much later
timer_func();

我是100％我在调用this.clusters之前在我的代码中初始化了这里所谓的timer_func()，但显然我尝试访​​问的变量是未定义的（而如果我将其打印在其他地方以外的地方）超时不是）。有什么建议吗？感谢。

Answer 1

我说问题在于你如何拨打timer_func()，而不是使用setInterval()。如果您希望 this内的timer_func() 引用您通过this 外部设置属性的同一对象{{1然后按如下方式调用它：

timer_func()

Answer 2

永远不会在对象上定义属性clusters，也不会将参数clusters传递给内部函数。您可以进入两个方向之一，指定属性或传递参数。

指定属性

var timer_func = function(){
    this.clusters = ["cluster1", "cluster2"];
    var that = this;
    var inspect = function(clusters){

        var clength = "";

        for(var i = 0; i < that.clusters.length; i++){   //---> undefined that.clusters.length
            clength += that.clusters[i].processes.length + ",";
        }

        console.log(clength);
    }

    var inspector = setInterval(inspect, 1000);
};
//much later
timer_func();

传递参数

var timer_func = function(){
    var that = this;
    var inspect = function(clusters){

        var clength = "";

        for(var i = 0; i < clusters.length; i++){
            clength += clusters[i].processes.length + ",";
        }

        console.log(clength);
    }

    var inspector = setInterval(function(){
       var clusters = ["cluster1", "cluster2"]; 
       inspect(clusters)
    }, 1000);
};
//much later
timer_func();

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