This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
setInterval() only running function once
I'm using the following script to understand the concept of function context. I'm excepting the alerts to start from 20 onwards and repeat. But it goes quite after displaying 20.
When using call method and providing the o2, it should get the value 20 and repeat from there on.
<script type="text/javascript">
var o2 = {
local: 20
}
var local=0;
function someFuncObject(){
alert('Thats method object again ' + this.local++);
}
// window.setInterval(someFuncObject, 2000); //This works perfect!!!
window.setInterval(someFuncObject.call(o2), 2000); // This does not, why?
</script>
On the otherhand if I use window.setInterval(someFuncObject, 2000); it works fine and repeats again and again. What's the problem?
someFuncObject.call(o2) actually calls the function. This means, what gets passed into setInterval is what is returned from someFuncObject(). What setInterval expects as parameter is a function itself, not what the function returns.
If you want to control the value of this inside someFuncObject, you can use an anonymous function like:
window.setInterval(function() {
someFuncObject.call(o2);
}, 2000);
Related
This question already has answers here:
setTimeout calls function immediately instead of after delay
(2 answers)
Closed 6 years ago.
I have a recursive SetTimeout function that clicks a filter on my page after the filters have loaded (they're loaded through Ajax, so not available immediately on page load).
$scope.clickFilter = function () {
var filter = $('.filter-item')
.find('input[value="' + $scope.activeFilter + '"]');
if (filter.length < 1) {
setTimeout($scope.clickFilter(), 1000);
} else {
$(filter).trigger("click");
}
}
However, when the filters take a long time to load, I get "Uncaught RangeError: Maximum call stack size exceeded(…)"
How do I prevent this and make sure it runs until completion?
The problem is here:
setTimeout($scope.clickFilter(), 1000);
Putting () after the function reference means that you want the function to be called, immediately, at that point in the code. What you probably want instead is something like:
setTimeout($scope.clickFilter.bind($scope), 1000);
which will
pass a function reference to setTimeout(), as is required, and
ensure that the function will be invoked with the proper this value (what the .bind() part does)
Once you get it working, the term "recursive" isn't really appropriate. Yes, the function is referencing itself when it arranges for the call after the timer expires, but it's not directly calling itself; it's asking something else (the timer mechanism) to call it later.
This question already has answers here:
setTimeout in for-loop does not print consecutive values [duplicate]
(10 answers)
Closed 5 years ago.
I'm new to javascript and I'm having trouble using the setInterval() function properly.
Basically I want to call a function at different given intervals for different parameters both of which I have in lists.
I have a function called myfunction. I have a list called myparam with all of the variables I want to pass this function. And finally I have a list called myfrequency which is the time in millis that I want between each call of myfunction with the parameter given in myparam. I'm trying something like this but it's not working:
for(i=0;i<myparam.length();i++;){
setInterval(function(){myfunction(myparam[i]);},myfrequency[i]);
}
The result of the above code is that it works only for the last index. myfunction gets called at the correct interval with the correct parameter for ONLY the last value in myparam.
Why does this happen? Is my thinking that setInterval() sets up the calling of a function at an interval incorrect?
Well it's because setInterval has a delay which means when the interval runs
the loop is already been finish
To do that just create another function which will start your interval
function StartInterval(index, frequency) {
setInterval(function(){
myfunction(index);
},frequency);
}
Then inside your loop just call this function and pass something
for(i=0;i<myparam.length;i++){
StartInterval(myparam[i], myfrequency[i])
}
/** set what value you want **/
var myparam = [10,20,30];
var myfrequency = [1000,2000,3000];
function myfunction(index) {
console.log(index);
}
function StartInterval(index, frequency) {
setInterval(function(){
myfunction(index);
},frequency);
}
for(i=0;i<myparam.length;i++){
StartInterval(myparam[i], myfrequency[i])
}
This question already has answers here:
setTimeout calls function immediately instead of after delay
(2 answers)
Closed 6 years ago.
I have a recursive SetTimeout function that clicks a filter on my page after the filters have loaded (they're loaded through Ajax, so not available immediately on page load).
$scope.clickFilter = function () {
var filter = $('.filter-item')
.find('input[value="' + $scope.activeFilter + '"]');
if (filter.length < 1) {
setTimeout($scope.clickFilter(), 1000);
} else {
$(filter).trigger("click");
}
}
However, when the filters take a long time to load, I get "Uncaught RangeError: Maximum call stack size exceeded(…)"
How do I prevent this and make sure it runs until completion?
The problem is here:
setTimeout($scope.clickFilter(), 1000);
Putting () after the function reference means that you want the function to be called, immediately, at that point in the code. What you probably want instead is something like:
setTimeout($scope.clickFilter.bind($scope), 1000);
which will
pass a function reference to setTimeout(), as is required, and
ensure that the function will be invoked with the proper this value (what the .bind() part does)
Once you get it working, the term "recursive" isn't really appropriate. Yes, the function is referencing itself when it arranges for the call after the timer expires, but it's not directly calling itself; it's asking something else (the timer mechanism) to call it later.
This question already has answers here:
Referencing "this" inside setInterval/setTimeout within object prototype methods [duplicate]
(2 answers)
Closed 6 years ago.
I'm having issues with the window.setInterval() method. Below is an example of the structure, the method "repeat" is called repeatedly, however I cannot call any methods inside "repeat". In the example when I instantiate manager (let m = new manager()) it will print "Before Print", but will not print out the log from the printStuff method, or the "After Print" message.
Does anyone know why this is happening? Obviously this isn't my actual code as it's simple enough to not be in separate functions, however my actual code needs to call many functions in the "repeat" function and it will stop execution when it finds a call to another function.
class manager{
constructor(){
window.setInterval(this.repeat, 5000);
}
repeat(){
console.log("Before Print");
this.printStuff();
console.log("After Print");
}
printStuff(){
console.log("Print Stuff");
}
Set interval will take take the this.repeat out of the context you need to either explicitly 'bind' the method using
setInterval(this.repeat.bind(this), 5000)
or
setInterval(()=>this.repeat(), 5000)
This question already has answers here:
Calling functions with setTimeout()
(6 answers)
Closed 6 years ago.
-so i am obviously trying to get two functions to run automatically whilst on a timer using setTimeout. However i am not to sure how it works. All i can see when i search it up is it in a function. so how do i have it outside a function?
function ChangeImage() {
if(position < TrafficL.length) {
document.getElementById("myImage").src = TrafficL[position];
position++
}
}
function RestartPos() {
if (position==3)
document.getElementById("myImage").src = TrafficL["position"]
position=0
var setTimeout = (ChangeImage(),1500)
var setTimeout = (RestartPos(),6000)
You sould call setTimeout as a function:
setTimeout(ChangeImage,1500);
setTimeout(RestartPos,6000);
ChangeImage and RestartPos are like variables referencing a function. If you place parentheses behind them means, you are calling them immediately, but you want to call them after a given time.
You can store the value return by setTimeout() in a variable though, but it's only for cancelling the countdown later:
// nothing happens, because the timeout was cancelled in 1.5s
var t = setTimeout(ChangeImage,1500);
clearTimeout(t);