如果margin-left == 200px，则发生火灾事件;

Question

I'm trying to create a listener kind of thing in jQuery. What I want to do is check all the time, if an divs margin-left == 200px and then fire an event. But I have no idea how to do that. Maybe it's better, that the div calls the event function, when it's margin-left == 200px, but I'm not even sure, if that's possible.

Any help will be very appreciated.

Answer 1

The following function will check every 1 second whether an element with the class elementClass has a margin-left set as 200px . If so, an alert will be triggered (as an example).

$(document).ready(function(){
   setInterval(function(){
      if ($(".elementClass").css("marginLeft")=='200px'){
         //do something here
         alert("margin is 200px");
      }
   }, 1000);
});

---

However, this code will then trigger the event every second that the margin-left is 200px . The following will only trigger the event the first time the element has been detected with the 200px margin-left:

 var eventtrig = 0;
 $(document).ready(function(){
   setInterval(function(){
      if ($(".elementClass").css("marginLeft")=='200px' && eventtrig=0) {
         //do something here
         alert("margin is 200px");
         eventtrig=1;
      }
      else {
         eventtrig=0;
      }
   }, 1000);
});

Answer 2

You can check "all the time" by doing a setinterval( ) of say 1 second and then, in the handler for the clock event, check the div's left margin and perhaps alert( ) when/if it ever gets to 200.

EDIT: as a point of information: the process of checking every once in a while -- ie, every second -- is called "polling."