javascript - 如何在不使用 setTimeout 的情况下异步运行 javascript 函数？

Question

它是服务器端 Javascript（犀牛引擎），因此 setTimeout 不可用。如何异步运行函数？

Answer 1

您可以使用java.util.Timer和java.util.TimerTask滚动您自己的设置/清除超时和设置/清除间隔功能：

var setTimeout,
    clearTimeout,
    setInterval,
    clearInterval;

(function () {
    var timer = new java.util.Timer();
    var counter = 1; 
    var ids = {};

    setTimeout = function (fn,delay) {
        var id = counter++;
        ids[id] = new JavaAdapter(java.util.TimerTask,{run: fn});
        timer.schedule(ids[id],delay);
        return id;
    }

    clearTimeout = function (id) {
        ids[id].cancel();
        timer.purge();
        delete ids[id];
    }

    setInterval = function (fn,delay) {
        var id = counter++; 
        ids[id] = new JavaAdapter(java.util.TimerTask,{run: fn});
        timer.schedule(ids[id],delay,delay);
        return id;
    }

    clearInterval = clearTimeout;

})()

Answer 2

查看Rhino 示例页面Multithreaded Script Execution上的示例。基本上，JavaScript 不直接支持线程，但您可以使用 Java 线程来实现您正在寻找的东西。

Answer 3

另一个使用ScheduledThreadPoolExecutor的版本，与 Rhino 1.7R4 兼容，由@Nikita-Beloglazov提出：

var setTimeout, clearTimeout, setInterval, clearInterval;

(function () {
    var executor = new java.util.concurrent.Executors.newScheduledThreadPool(1);
    var counter = 1;
    var ids = {};

    setTimeout = function (fn,delay) {
        var id = counter++;
        var runnable = new JavaAdapter(java.lang.Runnable, {run: fn});
        ids[id] = executor.schedule(runnable, delay, 
            java.util.concurrent.TimeUnit.MILLISECONDS);
        return id;
    }

    clearTimeout = function (id) {
        ids[id].cancel(false);
        executor.purge();
        delete ids[id];
    }

    setInterval = function (fn,delay) {
        var id = counter++;
        var runnable = new JavaAdapter(java.lang.Runnable, {run: fn});
        ids[id] = executor.scheduleAtFixedRate(runnable, delay, delay, 
            java.util.concurrent.TimeUnit.MILLISECONDS);
        return id;
    }

    clearInterval = clearTimeout;

})()

参考：https ://gist.github.com/nbeloglazov/9633318