javascript - 未捕获的类型错误 : Cannot call method 'terminate' of null (web worker)

Question

我正在尝试为我的游戏添加计时器。

这是下面的web worker:

startTimer();
    var w = null;
    function startTimer()
    {
        // First check whether Web Workers are supported
        if (typeof (Worker) !== "undefined") {
            // Check whether Web Worker has been created. If not, create a new Web Worker based on the Javascript file simple-timer.js
            if (w == null) {
                w = new Worker("../js/Timer.js");
                console.log(w);
            }
            // Update timer div with output from Web Worker
            w.onmessage = function(event) {
                document.getElementById("timer").innerHTML = event.data;
            };
        } else {
            // Web workers are not supported by your browser
            document.getElementById("timer").innerHTML = "Sorry, your browser does not support Web Workers ...";
        }
    }

// function to stop the timer
    function stopTimer()
    {
        w.terminate();
        timerStart = true;
        w = null;
    }
};

这是我的Timer.js 文件:

var i = 0;

function timedCount()
{
    i = i + 1;
    postMessage(i);
    setTimeout("timedCount()", 200);
}

timedCount();

这是我想出的错误，当我试图停止计时器时。我还添加了一条控制台消息，如您在图片中所见。

编辑:解决方案找到问题原因了，主要是stopTimer()函数被调用超过1次导致null终止。

Answer 1

在上面的代码中，您必须首先将 w 设置为 null。

    var w = null;

初始化为:

    var w;