How to start setInterval loop immediately? [duplicate]
In a simple setInterval
setInterval(function() {
// Do something every 9 seconds
}, 9000);
The first action will happen after 9 seconds (t=9s
). How to force the loop to perform the first action immediately (t=0
)?
I think it is due to the mechanism of setInterval
to have Delay - Action - Delay - Action ...
loop; instead of Action - Delay - Action - Delay ...
loop.
EDIT: My function is indeed a loop as
setInterval(function(){
$('.test').each(function(idx){
var duration = 1000;
$(this).delay(duration*idx);
Some stuff here
});
}, 4000);
Keep it simple. You can use a named function instead of an anonymous function; call it and set an interval for it.
function doSomething() {
console.log("tick");
}
doSomething();
setInterval(doSomething, 9000);
Create a scope if necessary:
(function() {
function doSomething() {
console.log("tick");
}
doSomething();
setInterval(doSomething, 9000);
})();
Finally, the following works without creating or affecting x
:
setInterval(function x() {
console.log("tick");
return x;
}(), 9000);
Sometimes I use this pattern...
(function me() {
// Do something every 9 seconds
setTimeout(me, 9000);
})();
It's not quite the same, as it will wait until the do something is executed before waiting ~9 seconds to call it again. But, this is often useful so events on the event queue do not stack up needlessly (however unlikely it is some code will take 9 seconds to run :)
Note that in older IEs, the me
will leak to the outside scope.