javascript - 如果延迟超过 2147483648 毫秒，setTimeout 立即触发

Question

问题

如果delay超过 2147483648 毫秒（24.8551 天），该函数将立即触发。

例子

setTimeout(function(){ console.log('hey') }, 2147483648) // this fires early
setTimeout(function(){ console.log('hey') }, 2147483647) // this works properly

我在 Chrome v26 和 Node.js v8.21 下试过

Answer 1

setTimeout 的上限为0x7FFFFFFF（或2147483647十进制）

这是因为 setTimeout 使用一个 32 位整数来存储它的延迟值，所以任何高于此值都会导致问题

如果您想要在 X 天后触发的超时，您可以尝试使用setInterval像这样的较低延迟值

function setDaysTimeout(callback,days) {
    // 86400 seconds in a day
    var msInDay = 86400*1000; 

    var dayCount = 0;
    var timer = setInterval(function() {
        dayCount++;  // a day has passed

        if(dayCount == days) {
           clearInterval(timer);
           callback.apply(this,[]);
        }
    },msInDay);
}

然后你会像这样使用它

setDaysTimeout(function() {
     console.log('Four days gone');
},4); // fire after 4 days

Answer 2

由于您仅限于 32 位，因此只需将 setTimeout 包装在递归函数中，如下所示：

function setLongTimeout(callback, timeout_ms)
{

 //if we have to wait more than max time, need to recursively call this function again
 if(timeout_ms > 2147483647)
 {    //now wait until the max wait time passes then call this function again with
      //requested wait - max wait we just did, make sure and pass callback
      setTimeout(function(){ setLongTimeout(callback, (timeout_ms - 2147483647)); },
          2147483647);
 }
 else  //if we are asking to wait less than max, finally just do regular setTimeout and call callback
 {     setTimeout(callback, timeout_ms);     }
}

这并不太复杂，应该可以扩展到 1.7976931348623157E+10308 的 javascript 数字的限制，到那个毫秒数，我们都将死去。

也可以这样做，以便您能够设置LongTimeout，您可以修改函数以接受通过引用传递的对象，从而将范围保留回调用函数：

function setLongTimeout(callback, timeout_ms, timeoutHandleObject)
{
 //if we have to wait more than max time, need to recursively call this function again
 if(timeout_ms > 2147483647)
 {    //now wait until the max wait time passes then call this function again with
      //requested wait - max wait we just did, make sure and pass callback
      timeoutHandleObject.timeoutHandle = setTimeout(function(){ setLongTimeout(callback, (timeout_ms - 2147483647), timeoutHandleObject); },
          2147483647);
 }
 else  //if we are asking to wait less than max, finally just do regular setTimeout and call callback
 {     timeoutHandleObject.timeoutHandle = setTimeout(callback, timeout_ms);     }
}

现在您可以调用超时，然后在需要时取消它，如下所示：

var timeoutHandleObject = {};
setLongTimeout(function(){ console.log("Made it!");}, 2147483649, timeoutHandleObject);
setTimeout(function(){ clearTimeout(timeoutHandleObject.timeoutHandle); }, 5000);