clearTimeout如果存在 [英] clearTimeout if exists

问题描述

timer_gear 仅在我按某个按钮（直到5秒）的情况下才存在。但是可以随时调用另一个函数。在此功能中，我清除计时器并重新启动它。但首先我必须检查对象是否存在，否则我收到此错误：
未捕获的ReferenceError：未定义timer_gear

timer_gear exist only in case if I press some button (until 5 sec). But there is another function it can be called any time. In this function I clear the timer and restart it. But first I have to check if the object exists otherwise I get this error: Uncaught ReferenceError: timer_gear is not defined

你能帮我解决一下吗？这些不起作用。

Could you help me to solve this? These does not work.

if(timer_gear!="undefined")clearTimeout(timer_gear);

if(timer_gear)clearTimeout(timer_gear);

EDIT1：
首先我拼错了我的问题：if（！timer => if（timer）
EDIT2：

first I misspelled my question: if(!timer => if(timer

完整代码为：

function hide_gear(){
    $('#gear_div').animate({opacity: 0}, 1000);
    delete timer_gear; //EDIT3: destroy object
}

...

/*gear*/
$('#gear').click(function(){
    $('#gear_div').animate({
        opacity: 1,
      }, 1000, function() {
        timer_gear = setTimeout("hide_gear();",5000);
      });
});
$('#gear').mousemove(function(){
    if( ? ? ? )
    {
        clearTimeout(timer_gear);
        timer_gear = setTimeout("hide_gear();",5000);
    }

});

结果：

Results:

timer_gear// Uncaught ReferenceError timer_gear is not defined
timer_gear != undefined // Uncaught ReferenceError: timer_gear is not defined
typeof timer_gear !== "undefined" // WORKS
typeof timer_gear != "undefined" // WORKS, just tired it
var timer_gear; //at the begining - WORKS, but I did not wanted a new variable if its not necessary

谢谢你的答案！

推荐答案

第一个应该是：

if(typeof timer_gear !== "undefined"){
  clearTimeout(timer_gear);
}

第二个，但是这个不起作用如果 timer_gear 未定义，所以你应该使用 typeof 一个：

And the 2nd, but this won't work if timer_gear is not defined, so you should use the typeof one above:

if(timer_gear){
  clearTimeout(timer_gear);
}

这篇关于clearTimeout如果存在的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！