I want to pause 1 second for every time it loops, it is usually easy to do similar pauses on other cases, but when working with loops, it seems it get harder:
for (var i=0 ; i < 10 ; i++) {
document.write (i + "<br>");
// I want to wait 1 second here
}
This is one example of my thousands failed attempts:
function writeMsg (index) {
document.write (index + "<br>");
}
for (var i=0 ; i < 10 ; i++) {
setTimeout (writeMsg(i), 1000);
}
Any ideas of how to get this to work?
This function works more like a normal for loop while it isn't
You need to take into account that a for gets 3 arguments inbetween semicolons.
Before starting (ie var i=0 you define a variable)
A condition before running the code again (ie i < 10 while i is under 10)
An action everytime it finishes the code again (i++ add one to i)
Code
(function() {
// Define a variable
var i = 0,
action = function() {
// Condition to run again
if (i < 10) {
document.write(i + "<br>");
// Add one to i
i++;
setTimeout(action, 1000);
}
};
setTimeout(action, 1000);
})();
Here is a jsfiddle for this code demonstrating its working:
http://jsfiddle.net/sg3s/n9BNQ/
You pass the return value of a function call to setTimeout instead of a function. Try the following code:
for (var i = 0; i < 10; i++) {
(function(i) {
setTimeout(function() {
writeMsg(i);
}, 1000*i);
})(i);
}
In case you wonder why the call is wrapped inside an anonymous function: Without that function each setTimeout callback would receive the same i so when the callbacks fire it would always be 10. The anonymous function creates a new i inside that is not connected to the loop variable.
Classic function-in-a-loop problem. One archetypal solution:
function createCallback(i) {
return function () {
writeMsg(i);
};
}
function writeMsg (index) {
document.write (index + "<br>");
}
for (var i=0 ; i < 10 ; i++) {
setTimeout (createCallback(i), 1000*i);
}
The 10 timeouts are all based on the time that setTimeout() is called. So, they are all triggered at the same time.
for (var i=0; i < 10; i++) {
(function(idx){
setTimeout(function(){
document.write(idx+"<br/>");
},1000*idx);
})(i);
};
try this it will definitely help who all are think how to make it work wait property inside For Loop...
try this code in this URL http://www.shopjustice.com/the-collections/C-10329.
var var2;
var tmp;
var evt;
var i=0;
var res = document.getElementsByClassName('mar-plp-filter-content nav nav--stacked')[0].children.length;
tmp = document.getElementsByClassName('mar-plp-filter-content nav nav--stacked')[0].children;
function myfunc()
{
if(i<res)
{
var2 = tmp[i].getElementsByTagName("span")[0].getElementsByClassName("inverted")[0];
// alert(var2.innerHTML);
var evObj = document.createEvent('MouseEvents');
evObj.initEvent( 'mouseover', true, false );
var2.dispatchEvent(evObj);
var2.style.backgroundColor="GREEN";
i++;
setTimeout(myfunc,3000);
}
};
setTimeout(myfunc,3000);
Related
function generalFunctionThatHappensWhenYouClickAButton(){
for (let i = 0; i < 1000; i++){
setTimeout(animateSquares(), 10000);
}
}
function animateSquares(){
topPositionThatAdds++;
console.log(topPositionThatAdds);
}
The function animateSquares() will execute 1000 times as planned, but all at the same time and not waiting 10,000 ms for each execution, as I planned to.
Does anyone know why this is happening?
Thank you for your time.
Well, that is because inside your setTimeout function, you're not just specifying your handler/callback function, instead you are calling it. In case of any callback functions, if you call them using ( ), they will always be executed immediately.
Therefore, your code shouldn't be this:
setTimeout(animateSquares(), 10000);
Instead, it should be this:
setTimeout(animateSquares, 10000); //specify the callback, don't call it using ( )
As you want there to be a 10ms delay between each callback execution, you can go about that in the following way:
let topPositionThatAdds = 0;
function generalFunctionThatHappensWhenYouClickAButton() {
for (let i = 0; i < 1000; i++) {
setTimeout(animateSquares, 10000 * (i + 1));
}
}
function animateSquares() {
topPositionThatAdds++;
console.log(
topPositionThatAdds
);
}
generalFunctionThatHappensWhenYouClickAButton();
Now if you wanted to use a parameter in your callback (topPositionThatAdds), then you can do something like the following.
function topPositionThatAdds(i){
console.log('square ', i);
};
function generalFunctionThatHappensWhenYouClickAButton() {
for(var i = 0;i < 1000; i++){
let j = i;
setTimeout(
function() {topPositionThatAdds(j)}
, 10000 * (j + 1));
}
}
generalFunctionThatHappensWhenYouClickAButton();
I'm building a simon game. And after each round the player should see the moves he must play in the next round. So i created a function showMoves which flashes the square he has to play. The problem is that the function is not showing anything. Can anyone tell me what did i miss?
// the effect
function flasher(index) {
$(moves[index]).fadeIn(50).fadeOut(50).fadeIn(50).fadeOut(50).fadeIn(100);
}
var interval2;
// show the moves that supposed to be played
function showMoves() {
for (var i = 0; i < moves; i++) {
if (i === 0) {
interval2 = setTimeout(flasher(i), 1000);
} else {
interval2 = setTimeout(flasher(i), (i+1) * 1000);
}
}
}
setTimeout accepts a function as a first parameter. I assume that by calling flasher you tried to avoid this situation. In you case, this should be done like this:
function showMoves() {
for (var i = 0; i < moves; i++) {
if (i === 0) {
interval2 = setTimeout(function(i) {return function() {flasher(i)}}(i), 1000);
} else {
interval2 = setTimeout(function(i) {return function() {flasher(i)}}(i), (i+1) * 1000);
}
}
}
The setTimeout and setInterval are a little diffrent than we think about them.
They are save some event on specified times that will be fired in its times. Because of this they has a problem with loops:
for(i=0;i<3;i++)
{
setTimeout(function(){alert(i)}, i*1000);
}
after ending the loop the browser has 3 jobs to do:
alert(i) after 1 second
alert(i) after 2 seconds
alert(i) after 3 seconds
But what is the value of 'i'. If you are in c# programming after ending the loop 'i' will be disposed and we have not that.
But javascript does not dispose 'i' and we have it yet. So the browser set the current value for i that is 3. because when 'i' reaches to 3 loop goes end. Therefor Your browser do this:
alert(3) after 1 second
alert(3) after 2 seconds
alert(3) after 3 seconds
That is not what we want. But if change the above code to this:
for(i=0;i<3;i++){
(function (index)
{
setTimeout(function () { alert(index); }, i * 1000);
})(i);
}
We will have:
alert(0) after 1 second
alert(1) after 2 seconds
alert(2) after 3 seconds
So as Maximus said you mast make the browser to get value of i currently in loop. in this way:
setTimeout(function(i) {return function() {flasher(i)}}(i), (i+1) * 1000);
i does not leave out until end of loop and must be get value just now.
What I can derive from your code is that moves is an array, but you're using it as if it's an integer in the for loop. And that's why nothing happens at all.
Replace:
for (var i = 0; i < moves; i++) {
With:
for (var i = 0; i < moves.length; i++) {
And you should see things happening.
But you will notice flasher is called immediately, without timeout. And that's because the result of flasher is set to be called, instead of flasher itself.
Other answers here suggest using an wrapper function, but this requires workarounds to correctly pass the index to the function called by setTimeout.
So assuming that it doesn't have to run in IE8 and below, the following is the most concise solution:
setTimeout(flasher.bind(null, i), (i+1) * 1000)
Full working example:
var moves = [1, 2, 3, 4];
function flasher(index) {
console.log('move', moves[index]);
}
var interval2;
// show the moves that supposed to be played
function showMoves() {
for (var i = 0; i < moves.length; i++) {
interval2 = setTimeout(flasher.bind(null, i), (i+1) * 1000);
}
}
showMoves()
I want to set 8 timeouts from a for loop. i have jquery ids: ir1,ir2...,ir8. Why is the following not working:
var i = 1;
for (i; i<9; i++ ){
setTimeout( $('#ir'+i).hide(),100*i);
}
http://jsbin.com/OrUVoRi/1/edit
var i = 0, elements = [];
//save jquery calls for performance reasons
for (i = 0; i<9; i++){
elements[i] = $('#ir'+i);
}
//you can make this function custom
var hide = function(i){
elements[i].hide();
};
//the callback loop
for (i = 0; i<9; i++){
//bind i value to the hide function
setTimeout( hide.bind(this, i), 1000*i );
}
setTimeout() should be
setTimeout(function(){
$('#ir'+i).hide()
},100*i);
updated.
as #royi namir mentioned, the issue is because of closure(scope) , call a self invoking function , pass i as argument , increased the timeout value to 1000 ... just as an example
var i = 1;
for (i; i<9; i++){
(function(a){
setTimeout(function(){
$('#ir'+a).hide();
},1000*a);
})(i);
}
fiddle
You question is blurred : I'll explain :
in first glance you're having a closure problem :
solution :
var i = 1;
for (i; i<9; i++){
(function(a){
setTimeout(function(){
$('#ir'+a).hide();
},1000*a);
})(i);
}
Also , since all your timeouts execute in burst -you added an increased delay : 100*i;
Among other solutions - here is mine : http://jsbin.com/EpaceSaJ/5/edit
the difference is that in your case - the functions will be at exact 100*i regardless the execution of inner code
While - in my solution : the timeout will be start after each end of last operation.
(function g(i,max){
setTimeout(function ( )
{
console.log(i); // <-- put your stuff here
if (i==max) return false;
g((++i),max);
}, 1000);
})(1,3); // <--loop values from 1 to 3 (9 at your case)
Well I did not know what exactly would be a good title for this because it is a most peculiar situation or I'm abnormally dumb.
Here's what im trying to do.
Create a simple <meter> tag which is new in HTML5. The main issue is with my javascript. Im trying to increment the value of the meter tag gradually in my javascript. But somehow it doesn't work the way i want.
JavaScript.
for (var i = 0; i <= 10; i++) {
var a = document.getElementById("mtr1");
setTimeout(function () {
console.log(i);
a.value = i;
}, 250);
}
I'm trying to increase the value of the meter gradually every 250 ms.This doesn't happen. Instead the meter jumps straight to 10.
What interested me was the value of i that i got in the console. I got instances of 10, instead of 1,2,3...10.
Why does this happen?
FIDDLE
It's a JavaScript closures' classic. Here i is an actual reference to the variable, not its copy. After you've iterated through the loop it has the value of 10, that's why all log invocations write 10 to log.
This should work better:
for (var i = 0; i <= 10; i++) {
var a = document.getElementById("mtr1");
setTimeout(function (i) {
return function() {
console.log(i);
a.value = i;
};
}(i), 250 * i);
}
Here the most inner i is the setTimeout's callback argument, not the variable which you've declared in the loop body.
You should read more about closures in JavaScript. When a variable gets closed over, it's the same exact variable, not a copy. Since setTimeout is asynchronous, the whole loop finishes before any of the functions run, therefore the i variable will be 10 everywhere.
DEMO
function incMtrAsync(max, delay, el) {
if (el.value++ < max) {
setTimeout(incMtrAsync.bind(null, max, delay, el), delay);
}
}
incMtrAsync(10, 250, document.getElementById("mtr1"));
The above implementation implements the loop using a recursive approach. Everytime inMtrAsync is called, it checks if the value of the meter reached the max value, and if not, registers another timeout with a callback to itself.
If you want to delay the initial increment as well, just wrap the first call in another timeout.
setTimeout(incMtrAsync.bind(null, 10, 250, document.getElementById("mtr1")), 250);
Nobody used setInterval, so here's my solution ( http://jsfiddle.net/Qh6gb/4/) :
var a = document.getElementById("mtr1");
var i = 0;
var interval = setInterval(function () {
console.log(i);
a.value = ++i;
if (i == 10) {
clearInterval(interval);
}
}, 250);
The problem you describe happens before the asyncronous call to setTimeout in your original version sees a value of 10 for i because that is its value at the moment the callback is executed.
So, this is a problem with the scope of the closure, to make it work you should make it like this:
for (var i = 0; i <= 10; i++) {
var a = document.getElementById("mtr1");
(function (i, a) {
setTimeout(function () {
console.log(i);
a.value = i;
}, 250);
})(i, a);
}
also, since a is always the same, this should be better:
var a = document.getElementById("mtr1");
for (var i = 0; i <= 10; i++) {
(function (i) {
setTimeout(function () {
console.log(i);
a.value = i;
}, 250);
})(i);
}
If then you want to see the counter "ticking up", this will make it visible:
var a = document.getElementById("mtr1");
for (var i = 0; i <= 10; i++) {
(function (i) {
setTimeout(function () {
console.log(i);
a.value = i;
}, 1000 * i);
})(i);
}
See http://jsfiddle.net/LDt4d/
It happens because you called setTimeout, which is "asynchronous". So setTimeout is called 10times but after whole loop is done then it is executed. Therefore, i = 10 in each call...
http://jsfiddle.net/Qh6gb/9/
there is the solution:
var i = 1,
meter = document.getElementById("mtr1");
function increase() {
meter.value = i++;
console.log(i);
if(i<=10) {
setTimeout(increase, 250);
}
}
setTimeout(increase, 250);
you can use timeout jquery plugin:. It is easier
However you should calculate your timeout ,
For you ,timeout=250*max=250*10=2500
So
$('meter').timeout(2500);
Demo
Run for loop inside the function instead of declaring a closure in every step of the loop.
JSFIDDLE: http://jsfiddle.net/Qh6gb/3/
var a = document.getElementById("mtr1");
setTimeout(function () {
for (var i = 0; i < 10; i++) {
console.log(i);
a.value = i;
}
}, 250);
I hope I understand right. Please try and tell me if you got solution.
var count = 0;
function increment(){
document.getElementById("meter").value = count;
count++;
if(count ==10)
count=0;
}
setInterval(increment, 250);
Please check with jsFiddle
You're creating multiple functions that are all being set off at the same time.
Multiply the timer by i for correct delay.
for (var i = 0; i <= 10; i++) {
var a = document.getElementById("mtr1");
setTimeout(function () {
console.log(i);
a.value = i;
}, 250 * i);
}
This is my code. What I want it to do is write 0, wait one sec, write 1, wait one sec, write 2, wait one sec, etc. Instead it writes 5 5 5 5 5
for(i = 0; i < 5; i++) {
setTimeout("document.write(i + ' ')", 1000);
}
http://jsfiddle.net/Xb7Eb/
1) You set all the timeouts to last 1 second at the same time. The loop doesn't wait for the timeout to occur. So you have 5 timeouts that all execute at the same time.
2) When the timeouts execute, the loop is long since complete and i has become 5. So once they execute, they all print "5"
3) document.write() writes somthing onto the page, in the same place it executes. I.e. if you have <script>document.write("xyz")</script> in the middle of a piece of text, it'll write "xyz" in the middle of the text. The timeouts, however, are not necessarily anywhere on the page. They exist only in code.
Here's a solution that's as close to yours as possible: http://jsfiddle.net/rvbtU/1/
var container = document.getElementById("counter");
for(i = 0; i < 5; i++) {
setTimeout("container.innerHTML += '" + i + " ';", 1000 * i);
}
However, that solution uses setTimeout's ability to evaluate a string as javascript, which is never a good idea.
Here's a solution that uses an anymous function instead: http://jsfiddle.net/YbPVX/1/
var container = document.getElementById("counter");
var writer = function(number) {
return function() { container.innerHTML += String(number) + " "; };
}
for(i = 0; i < 5; i++) {
setTimeout(writer(i), 1000 * i);
}
Edit: Forgot to save the 2nd fiddle. Whoops. Fixed now.
Most of the answers available are giving bad advice.* Specifically, you shouldn't be passing a string to setTimeout anymore (it still works, but it's discouraged), it's no longer 2000, there are better ways to do this.
setTimeout takes a function as the first parameter, and that's what you should do, however there are some issues when calling setTimeout in a loop.
This looks like it should work:
var i;
for ( i = 0; i < 5; i++ )
{
setTimeout(function(){
document.write( i + ' ' );
}, 1000 * (i + 1) );
}
But it doesn't. The issue is that by the time setTimeout executes the function, the loop will have incremented i to 5, so you'll get the same value repeated.
There are a few fixes. If you're willing to risk a with statement, you could try the following:
var i;
for ( i = 0; i < 5; i++ )
{
with( { i:i } )
{
setTimeout(function(){
document.write( i + ' ' );
}, 1000 * (i+1) );
}
}
Note that with is typically discouraged just like passing string values to setTimeout, so I don't really suggest this method of doing things.
The better way is to use a closure:
var i;
for ( i = 0; i < 5; i++ )
{
(function(i){
setTimeout(function(){
document.write( i + ' ' );
}, 1000 * (i+1) );
})(i);
}
To explain what's going on, the anonymous function wrapper (function(i){...code...}) executes immediately because it's wrapped in parens and passed i as a value:
(function(i){...code...})(i);
This forces the i variable that document.write uses to be a different one than what's being used in the for loop. You could even change the parameter used in the anonymous function wrapper if the difference gets too confusing:
(function(a){document.write(a+' ')})(i);
* when I started writing this question there were a number of answers describing how to fix the string to work with setTimeout, although they would technically work, they didn't include why they would work (because 'document.write("' + i + ' ");' evaluates i at the time of calling due to string concatenation, versus evaluating i at runtime like the previous version did), and they most certainly didn't mention that it's the bad old way of calling setTimeout.
try
var i = 1;
function timeout(){
document.write(i + ' ');
i++;
if (i == 5) return;
setTimeout(timeout, 1000);
}
timeout();
http://jsfiddle.net/nnJcG/1/
You have a problem with clousures, you can try this:
var timeout = function(){
var i = 0;
return function(){
document.write(i+ ' ');
i++;
if(i!==5)
setTimeout(timeout,1000);
};
}();
setTimeout(timeout,1000);
Here is the example in jsBin http://jsbin.com/uloyuc/edit
First of all, NEVER pass a string to setTimeout. Use a function, it's much cleaner.
Second, you have to "close over" the loop value. I bet this is what you want.
for(var i = 0; i < 5; i++) {
(function(i) {
setTimeout(function() {
document.write(i + ' ')
}, i * 1000);
}(i));
}
See more about you a self executing function to close over a loop value here http://www.mennovanslooten.nl/blog/post/62
And just cause I love it, here is the equivalent in CoffeeScript whihc has the do keyword to help out with just this case.
for i in [0..4]
do (i) ->
setTimeout ->
document.write "#{ i } "
, i * 1000
You can also work with setInterval and clearInterval:
var i = 0;
var f = setInterval(function() {
if(i == 4) clearInterval(f);
document.write(++i + ' ');
}, 1000);
I think this code is very readable.
You could try like this:
var tick_limit = 5; // Or any number you wish representing the number of ticks
var counter = 0; // Or any number you wish
var timer_interval = 1000; // Interval for the counter
var timer;
function timerTick()
{
if(counter < tick_limit)
{
// Execute code and increase current count
document.body.innerHTML+=(counter + ' '); // Append the counter value to the body of the HTML page
counter++;
timer = setTimeout(timerTick,timer_interval);
}
else
{
// Reset everything
clearTimeout(timer);
counter = 0;
}
}
function startCounter()
{
clearTimeout(timer); // Stop current timer
timer = setTimeout(timerTick,timer_interval); // Start timer with any interval you wish
}
...
// Start timer when required
startCounter();
...
This way, calling the startCounter a number of times will result in a single timer executing the code
You're triggering five timeouts at the same time.
I like Pindatjuh's answer, but here's another fun way to do it.
This way starts the next timeout when the previous one is finished:
// Wrap everything in a self executing anonymous function so we don't pollute
// the global namespace.
//
// Note: Always use "var" statments or you will pollute the global namespace!
// For example "for(i = 0; i < 5; i++)" will pollute the global namespace
// unless you have "var i; for(i = 0; i < 5; i++)" or
// "for(var i = 0; i < 5; i++)" & all of that is not in the global namespace.
//
(function() {
// "i" will be available within doThis()
// you could also pass "i" as an argument
var i = 0,
doThis = function() {
// setTimeout can take an anonymous function
// or a regular function. This is better than
// eval-ing a string.
setTimeout(function() {
document.write(i + ' ');
++i;
// Do the function again if necessary
if (i < 5) doThis();
}, 1000);
}
// Let's begin!
doThis();
})();
Working Example