有没有比下面的pausecomp函数(取自此处)更好的方法来设计JavaScript中的睡眠?

function pausecomp(millis)
{
    var date = new Date();
    var curDate = null;
    do { curDate = new Date(); }
    while(curDate-date < millis);
}

这不是JavaScript中的Sleep的重复-动作之间的延迟;我希望在函数的中间有一个真正的睡眠,而不是在代码执行之前有一段延迟。


当前回答

在Firebug(可能还有其他JavaScript控制台)中,只有在指定的睡眠时间(…)之后,点击enter后才会发生任何事情

function sleepFor(sleepDuration){
    var now = new Date().getTime();
    while(new Date().getTime() < now + sleepDuration){ /* Do nothing */ }
}

使用示例:

函数sleepFor(sleepDuration){var now=new Date().getTime();而(newDate().getTime()<now+sleepDuration){/*什么都不做*/}}函数sleepThenAt(){sleepFor(2000);console.log(“您好,JavaScript睡眠!”);}sleepThenAt()

注:仅用于调试和开发

其他回答

第一:

定义要执行的函数,如下所示:

function alertWorld(){
  alert("Hello, World!");
}

然后使用setTimeout方法安排其执行:

setTimeout(alertWorld, 1000)

注意两件事

第二个参数是以毫秒为单位的时间作为第一个参数,必须只传递函数的名称(引用),而不传递括号

我同意其他海报。忙着睡觉是个坏主意。

但是,setTimeout不支持执行。它在超时设置后立即执行函数的下一行,而不是在超时过期后执行,因此无法完成睡眠所能完成的任务。

方法是将你的功能分解为前后两部分。

function doStuff()
{
  // Do some things
  setTimeout(continueExecution, 10000) // Wait ten seconds before continuing
}

function continueExecution()
{
   // Finish doing things after the pause
}

确保你的函数名仍然准确地描述了每一块正在做的事情(即GatherInputThenWait和CheckInput,而不是funcPart1和funcPart2)

此方法实现了在超时之后才执行您决定的代码行的目的,同时仍然将控制权返回到客户端PC,以执行它排队的任何其他代码。

正如评论中指出的那样,这绝对不会在循环中工作。你可以做一些花哨的(丑陋的)黑客来让它在一个循环中工作,但总的来说,这只会导致灾难性的意大利面条代码。

为了测试,我需要一段忙碌的等待。我不想拆分代码,因为这需要很多工作,所以一个简单的for为我做了这件事。

for (var i=0; i<1000000; i++){                  
    // Waiting
}

我看不出这样做有什么坏处,这对我来说很有好处。

如果(像我一样)你在Rhino中使用JavaScript,你可以使用。。。

try
{
  java.lang.Thread.sleep(timeInMilliseconds);
}
catch (e)
{
  /*
   * This will happen if the sleep is woken up - you might want to check
   * if enough time has passed and sleep again if not - depending on how
   * important the sleep time is to you.
   */
}

我相信有一百万种方法可以做得更好,但我想我可以通过创建一个对象来尝试一下:

// execute code consecutively with delays (blocking/non-blocking internally)
function timed_functions()
{
    this.myfuncs = [];
    this.myfuncs_delays = []; // mirrors keys of myfuncs -- values stored are custom delays, or -1 for use default
    this.myfuncs_count = 0; // increment by 1 whenever we add a function
    this.myfuncs_prev    = -1; // previous index in array
    this.myfuncs_cur    = 0; // current index in array
    this.myfuncs_next  = 0; // next index in array
    this.delay_cur     = 0; // current delay in ms
    this.delay_default = 0; // default delay in ms
    this.loop = false;      // will this object continue to execute when at end of myfuncs array?
    this.finished = false;  // are we there yet?
    this.blocking = true;   // wait till code completes before firing timer?
    this.destroy = false;   // <advanced> destroy self when finished


    this.next_cycle = function() {
        var that  = this;
        var mytimer = this.delay_default;

        if(this.myfuncs_cur > -1)
            if(this.myfuncs_delays[this.myfuncs_cur] > -1)
                mytimer = this.myfuncs_delays[this.myfuncs_cur];

        console.log("fnc:" + this.myfuncs_cur);
        console.log("timer:" + mytimer);
        console.log("custom delay:" + this.myfuncs_delays[this.myfuncs_cur]);
        setTimeout(function() {
        // Time is up! Next cycle...
        that.cycle();

    }, mytimer);
}

this.cycle = function() {

    // Now check how far we are along our queue.. is this the last function?
    if(this.myfuncs_next + 1 > this.myfuncs_count)
    {
        if(this.loop)
        {
            console.log('looping..');
            this.myfuncs_next = 0;
        }
        else
            this.finished = true;
    }

    // First check if object isn't finished
    if(this.finished)
        return false;

    // HANDLE NON BLOCKING //
    if(this.blocking != true) // Blocking disabled
    {
        console.log("NOT BLOCKING");
        this.next_cycle();
    }

    // Set prev = current, and current to next, and next to new next
    this.myfuncs_prev = this.myfuncs_cur;
    this.myfuncs_cur  = this.myfuncs_next;
    this.myfuncs_next++;

    // Execute current slot
    this.myfuncs[this.myfuncs_cur]();

    // HANDLE BLOCKING
    if(this.blocking == true)  // Blocking enabled
    {
        console.log("BLOCKING");
        this.next_cycle();
    }

    return true;
};

// Adders
this.add = {
    that:this,

    fnc: function(aFunction) {
        // Add to the function array
        var cur_key = this.that.myfuncs_count++;
        this.that.myfuncs[cur_key] = aFunction;
        // Add to the delay reference array
        this.that.myfuncs_delays[cur_key] = -1;
    }
}; // end::this.add

// setters
this.set = {
    that:this,

    delay: function(ms) {
        var cur_key = this.that.myfuncs_count - 1;
        // This will handle the custom delay array this.that.myfunc_delays
        // Add a custom delay to your function container

        console.log("setting custom delay. key: "+ cur_key + " msecs: " + ms);
        if(cur_key > -1)
        {
            this.that.myfuncs_delays[cur_key] = ms;
        }
        // So now we create an entry on the delay variable
    },

    delay_cur:      function(ms) { this.that.delay_cur = ms; },
    delay_default:  function(ms) { this.that.delay_default = ms; },
    loop_on:        function()   { this.that.loop = true; },
    loop_off:       function()   { this.that.loop = false; },
    blocking_on:    function()   { this.that.blocking = true; },
    blocking_off:   function()   { this.that.blocking = false; },

    finished:            function(aBool) { this.that.finished = true; }
}; // end::this.set


// Setters
this.get = {
    that:this,

    delay_default: function() { return this.that.delay_default; },
    delay_cur:     function() { return this.that.delay_cur; }
    }; // end::this.get

} // end:::function timed_functions()

使用方式如下:

// // // BEGIN :: TEST // // //

// Initialize
var fncTimer = new timed_functions;

// Set some defaults
fncTimer.set.delay_default(1000);
fncTimer.set.blocking_on();
// fncTimer.set.loop_on();
// fncTimer.set.loop_off();


// BEGIN :: ADD FUNCTIONS (they will fire off in order)
fncTimer.add.fnc(function() {
    console.log('plan a (2 secs)');
});
fncTimer.set.delay(2000); // Set a custom delay for previously added function

fncTimer.add.fnc(function() {
    console.log('hello world (delay 3 seconds)');
});
fncTimer.set.delay(3000);

fncTimer.add.fnc(function() {
    console.log('wait 4 seconds...');
});
fncTimer.set.delay(4000);

fncTimer.add.fnc(function() {
    console.log('wait 2 seconds');
});
fncTimer.set.delay(2000);

fncTimer.add.fnc(function() {
    console.log('finished.');
});
// END :: ADD FUNCTIONS


// NOW RUN
fncTimer.cycle(); // Begin execution


// // // END :: TEST // // //