How to pass a variable after setInterval completes? - javascript

I have the following code. A fiddle I started which is an isolated version of something I am trying to do.
var height;
var count = 0;
var setHeight = setInterval(function() {
count++;
console.log('count');
if ( count > 10)
{
console.log('done');
height = 20;
clearInterval(setHeight);
}
},100);
console.log('this is the height -> ' + height);
What I would expect (or want to happen) is for the value of height = 20; to be outputted in my console.log. The end goal would be to retrieve a variable from my setInterval function after the interval has been cleared.
Right now I get .. this is the height -> undefined
FIDDLE:
http://jsfiddle.net/GNvG6/8/
What I am trying to accomplish:
So the underlying issue is this. I have a function that runs before some elements are loaded in the DOM. So what I am trying to do is keep running the function until an instance of that element exists. Once that happens I then intend to get the height of that element and hand it off to another variable. I am not sure If this will resolve my issue, but I figure if I can get this to work I can at least test it out.

var height;
var count = 0;
var setHeight = setInterval(function() {
count++;
console.log('count');
if ( count > 10)
{
console.log('done');
height = 20;
reportHeight(height);
clearInterval(setHeight);
}
},100);
function reportHeight(height){
console.log('this is the height -> ' + height);
}
console output is
(11) count
done
this is the height -> 20

FIDDLE DEMO
var height = 0; // initial value
var count = 0;
var setHeight = setInterval(function() {
count++;
console.log('count and height is still:'+ height); // height is always 0
if ( count > 10){
height = 20;
console.log('done and height is:'+ height); // height is finally 20
clearInterval(setHeight);
}
},100);

As you're using jQuery, you could also use $.Deferred.
// wait for 3 + (0..2) seconds
setTimeout(function () {
$(document.body).append($("<strong>hello</strong>"));
}, 3000 + 2000 * Math.random());
function waitFor(test, interval) {
var dfd = $.Deferred();
var count = 0;
var id = setInterval(function () {
console.log(count++);
var val = test();
if (undefined !== val) {
clearInterval(id);
dfd.resolve(val);
}
}, interval);
return dfd.promise();
}
function waitForEl(selector, interval) {
return waitFor(function () {
var els = $(selector);
return (els.length > 0) ? els : undefined;
}, interval);
}
waitForEl("strong", 100).then(function (strong) {
console.log(strong, strong.height());
});
Example in this jsfiddle.

Related

SetInterval doesn't same when called again?

I'm making a simple program which increases a number incrementally for every 0.5 second. When I click start it works perfectly. But when I click restart, the increments go fine, but they don't increment every 0.5 sec and go pretty fast, and this happens when I am calling the same function? JS fiddle link below.
function runFunc(){
declare a variable interval outside function
var myInterval = null;
check if an interval is already running if yes clear it in order to avoid multiple interval running the same function which makes the interval became looks faster than the first time it's called
if (myInterval != null) {
clearInterval(myInterval);
}
also this is not correct
clearInterval(varName);
the parameter should be an interval which is like this
clearInterval(myInterval);
so your javascript code would be like this
var myInterval = null;
function runFunc(){
$('#counter').val(zero);
var varName = function(){
var number = Number($('#number').val());
var counter = Number($('#counter').val());
if(counter < number) {
counter++;
console.log(counter);
$('#counter').val(counter);
} else {
clearInterval(myInterval);
}
};
//check if an interval is already running if yes clear it
if (myInterval != null) {
clearInterval(myInterval);
}
myInterval = setInterval(varName, 500);
};
show.click(runFunc);
reset.click(function(){
$('#number').val(zero);
$('#counter').val(zero);
});
restart.click(runFunc);
u have to Declare a Variable for setInterval like "setIntervalID"
so stop it clearInterval("setIntervalID");
JSFIDDLE
var initialNumber = 10;
var zero = 0;
$('#number').val(initialNumber);
$('#counter').val(zero);
var show = $('#show');
var reset = $('#reset');
var restart = $('#restart');
var setIntervalID;
// console.log('initial value of number is ' + number);
// console.log(typeof number);
// console.log('initial value of counter is ' + counter);
var varName = function(){
var number = Number($('#number').val());
var counter = Number($('#counter').val());
if(counter < number) {
counter++;
console.log(counter);
$('#counter').val(counter);
}
}
function runFunc(){
$('#counter').val(zero);
setIntervalID = setInterval(varName, 500);
};
function stopFunc(){
clearInterval(setIntervalID);
};
function restartGO(){
stopFunc();
runFunc();
}
show.click(runFunc);
restart.click(restartGO);
reset.click(function(){
$('#number').val(zero);
$('#counter').val(zero);
});

Update progressbar in each loop

I have a progress bar that I update in a loop of many iterations.
https://jsfiddle.net/k29qy0do/32/
(open the console before you click the start button)
var progressbar = {};
$(function () {
progressbar = {
/** initial progress */
progress: 0,
/** maximum width of progressbar */
progress_max: 0,
/** The inner element of the progressbar (filled box). */
$progress_bar: $('#progressbar'),
/** Set the progressbar */
set: function (num) {
if (this.progress_max && num) {
this.progress = num / this.progress_max * 100;
console.log('percent: ' + this.progress + '% - ' + num + '/' + this.progress_max);
this.$progress_bar.width(String(this.progress) + '%');
}
},
fn_wrap: function (num) {
setTimeout(function() {
this.set(num);
}, 0);
}
};
});
$('#start_button').on('click', function () {
var iterations = 1000000000;
progressbar.progress_max = iterations;
var loop = function () {
for (var i = 1; i <= iterations; i++) {
if (iterations % i === 100) {
progressbar.set(i); //only updates the progressbar in the last iteration
//progressbar.fn_wrap(i); //even worse, since no output to the console is produced
}
}
}
//setTimeout(loop, 0);
loop();
});
The console is updated iteratively as expected.
However, the progressbar is not updating.
The problem is that the browser window seems to 'hang' until the loop finishes.
Only the console is updated, not the progressbar.
I have tried to add the setTimeout, as suggested below, in several places.
But that just makes things worse, because I then do not even get the console to output the progress while executing the loop.
Okay, I found a solution in the answer to this question:
Javascript: How to update a progress bar in a 'for' loop
var i = 0;
(function loop() {
i++;
if (iterations % i === 100) {
progressbar.set(i); //updates the progressbar, even in loop
}
if (i < iterations) {
setTimeout(loop, 0);
}
})();
My solution:
https://jsfiddle.net/ccvs4rer/3/
Lets break this down to steps
Step 1: Clean up HTML
Assuming the purpose of your question is to understand how to work the progress bar and not the styles or the labels (loading, please be patient, etc.). Lets just have the progress bar and the start button.
<div id='progressbar-outer' style="">
<div id='progressbar' style=""></div>
</div>
<button id="start_button">Start</button>
Step 2: The Styles
Lets make the progress bar visible to the user
#progressbar-outer {
height:2em;
border:5px solid #000;
width:15em;
}
#progressbar {
width:0%;
background-color:#F00;
height:100%;
}
Step 3: Using setTimeout where it belongs
In your code, you have used setTimeout to set the value of your progress bar. However, the for loop is still active.
for (var i = 1; i <= iterations; i++) {
if (iterations % i === 100) {
progressbar.set(i); //only updates the progressbar in the last iteration
//progressbar.fn_wrap(i); //even worse, since no output to the console is produced
//setTimeout(function() {
// progressbar.set(i);
//}, 0);
}
}
The use of setTimeout does not affect the rest of the code. Hence, the UI was held hostage till the loop ended. Try the following code.
$('#start_button').on('click', function () {
var iterations = 100;
progressbar.progress_max = iterations;
var loop = function (value) {
progressbar.set(value);
if (value < iterations) setTimeout(function () {
loop(value + 1)
}, 30);
else $('#progressbar').css('background-color', '#0F0');
}
loop(1);
});
Preview
Try this fiddle: https://jsfiddle.net/Ljc3b6rn/4/
What you really want is an Asynchronous loop to allow the browser to update the DOM in between iterations.
JSFiddle: http://jsfiddle.net/u5b6gr1w/
function delayedLoop(collection, delay, callback, context) {
context = context || null;
var i = 0,
nextInteration = function() {
if (i === collection.length) {
return;
}
callback.call(context, collection[i], i);
i++;
setTimeout(nextInteration, delay);
};
nextInteration();
}
Some HTML:
<div class="progress-bar"><div style="width: 0"></div></div>
A splash of CSS:
.progress-bar {
border: 1px solid black;
background-color: #f0f0f0;
}
.progress-bar div {
background-color: red;
height: 1.25em;
}
And some JavaScript to wire things together:
var progressBar = document.querySelector(".progress-bar div"),
items = [1,2,3,4,5,6,7,8,9,10];
delayedLoop(items, 500, function(item, index) {
var width = (item / items.length * 100) + "%";
progressBar.style.width = width;
progressBar.innerHTML = width;
});
My guess would be that all your progress updates are running in the same call stack. While JavaScript code is running, the DOM cannot update. Maybe this question will help you come up with a work-around.
What do you wnat to do? Why do you need it? You should only use a progressbar when you have to wait for something to finish. But we don't know what you do on your page.
If you want to display the progress of an ajax upload:
$.ajax({
...
xhr: function() {
var xhr = $.ajaxSettings.xhr();
$(xhr.upload).bind("progress", function(event) {
var e = event.originalEvent;
var percent = 0;
if (e.lengthComputable)
percent = Math.ceil(e.loaded/e.total*100);
$("#progress").width(percent+"%");
});
return xhr;
}
...
});
For images, you need an ajax call:
$.ajax({
method: "GET",
url: "http://example.com/path/image.jpg",
xhr: function() {/* see the code above*/ }
...
});
For getting the content of an uploaded file:
var reader = new FileReader();
reader.readAsText(uploadedFile);
$(reader).bind("progress", function(e) {
var percent = 0;
if (e.lengthComputable)
percent = Math.ceil(e.loaded/e.total*100);
$("#progress").css("width", percent+"%");
});
For large around of process, like math or appending a lot of divs that will take 10+ secons:
Main.js:
var worker = new Worker("Worker.js");
$(worker).bind("message", function(data) {
$("#progress").width((data*100)+"%");
});
Worker.js:
var total = 43483,
finished = 0,
doStuff = function() {
++finished;
return 1+1;
};
setInterval(function()
{
self.postMessage(finished/total);
}, 100);
for (var i = 0; i < total; ++i)
setTimeout(doStuff, i*10);
Because it's nice, and you want to tell the user there's a progress when there isn't, just animate the div:
$("#progress").animate({width: "100%"}, 3000);
You can use promises to wait until the width is set before continuing the loop.
Updating the progress bar for 1000000000 iterations will be slow if you go 1 by 1, so you might find it useful to decrease the update frequency.
Instead of a for loop, I used a recursive function that loops when the promise has been fulfilled.
set: function (num) {
var deferred = $.Deferred();
if (this.progress_max && num) {
this.progress = num / this.progress_max * 100;
var self = this;
self.$progress_bar.animate({"width": String(this.progress) + '%'}, "fast", function() {
deferred.resolve();
});
return deferred;
}
}
$('#start_button').on('click', function () {
var iterations = 1000000000;
var i = 0;
progressbar.progress_max = iterations;
var loop = function(){
i+=100000000;
if(i <= iterations){
progressbar.set(i).then(function(){
loop();
}); ;
}
};
loop();
});
https://jsfiddle.net/k29qy0do/34/
You have to use window.requestAnimationFrame, otherwise the browser will block until your loop is finished. The callback passed to requestAnimationFrame will get a timestamp as a parameter which you might be able to use for calculations of the progress.
This are my 2 takes on the question:
Using a web worker. The webworker blob code comes from here
Web worker code:
<script type="text/ww">
function loop(e) {
var data = JSON.parse(e.data);
var i = parseInt(data.i, 10);
var iterations = parseInt(data.iterations, 10);
while (iterations % ++i !== 100 && i <= iterations);
if(i <= iterations) {
self.postMessage(JSON.stringify({ i: i, iterations: iterations }));
}
}
self.onmessage = function(e) {
loop(e);
};
</script>
The code:
var ww = document.querySelector('script[type="text/ww"]'),
code = ww.textContent,
blob = new Blob([code], {type: 'text/javascript'}),
blobUrl = URL.createObjectURL(blob),
worker = new Worker(blobUrl);
worker.onmessage = function(e) {
var data = JSON.parse(e.data);
var i = parseInt(data.i, 10);
var iterations = parseInt(data.iterations, 10);
progressbar.set(i);
worker.postMessage(JSON.stringify({ i: i, iterations: iterations }));
}
$('#start_button').on('click', function () {
var iterations = 1000000000;
progressbar.progress_max = iterations;
worker.postMessage(JSON.stringify({ i: 0, iterations: iterations }));
});
The other idea hangs the UI thread, but changes the width visually, as I use requestAnimationFrame to break the counting, change width of the progressbar, and then continue the count.
function loopFrame(i, iterations) {
requestAnimationFrame(function() {
if (iterations % i === 100) {
progressbar.set(i);
}
if(i < iterations) {
loopFrame(i + 1, iterations);
}
});
}
$('#start_button').on('click', function () {
var iterations = 1000000000;
console.log(iterations);
progressbar.progress_max = iterations;
loopFrame(0, iterations);
});
Maybe this will be usefull.
var service = new Object();
//function with interrupt for show progress of operations
service.progressWhile = new Object();
service.progressWhile.dTime = 50; //step ms between callback display function
service.progressWhile.i = 0; //index
service.progressWhile.timer = 0; //start time for cycle
//#parametr arr - array for actions
//#parametr actionCallback - The function for processing array's elements
//#parametr progressCallback - function to display the array index
function progressWhile(arr, actionCallback, progressCallback) {
try {
var d = new Date();
service.progressWhile.timer = d.getTime();
log(service.progressWhile.i);
if (service.progressWhile.i >= arr.length) {
service.progressWhile.i = 0;
return;
}
while (service.progressWhile.i < arr.length) {
actionCallback(arr[service.progressWhile.i++]);
d = new Date();
if (d.getTime() - service.progressWhile.timer > service.progressWhile.dTime) {
break;
}
}
if (progressCallback != undefined)
progressCallback(service.progressWhile.i);
} catch (er) {
log(er);
return;
}
setTimeout(function () {
progressWhile(arr, actionCallback, progressCallback);
}, 0);
}
Here's updated fiddle
I used animate to make it a progress bar like look and feel.
Hope this will help you.
var progressbar = {};
$(function() {
progressbar = {
/** initial progress */
progress : 0,
/** maximum width of progressbar */
progress_max : 0,
/** The inner element of the progressbar (filled box). */
$progress_bar : $('#progressbar'),
/** Method to set the progressbar.*/
set : function(num) {
if (this.progress_max && num) {
this.progress = num / this.progress_max * 100;
console.log('percent: ' + this.progress + '% - ' + num + '/' + this.progress_max);
$('#progressbar').animate({
width : String(this.progress) + '%',
}, 500, function() {
// Animation complete.
});
}
},
fn_wrap : function(num) {
setTimeout(function() {
this.set(num);
}, 0);
}
};
});
$('#start_button').on('click', function() {
$('#progressbar').css('width', '0%');
var iterations = 1000000000;
progressbar.progress_max = iterations;
var loop = function() {
for (var i = 1; i <= iterations; i++) {
if (iterations % i === 100) {
progressbar.set(i);
//only updates the progressbar in the last iteration
}
}
}
loop();
});
Fiddler
[1]: https://jsfiddle.net/k29qy0do/21/

Running a function for each element

I am using the Peity js plugin to create donut charts on my page. I am trying to animate the chart for each of the .foo elements:
<span class="foo" data-value="10"></span>
$('.foo').each(function () {
var updateChart = $(this).peity('donut');
var text = "";
var i = 0;
function myLoop() {
setTimeout(function () {
text = i + "/12";
updateChart.text(text)
.change()
i = i + 0.2;
var maxValue = $(this).data("value");
if (i <= maxValue) myLoop();
}, 0.5)
}
myLoop();
});
However it won't work for some reason with no errors in console. If I remove the $('.foo').each(function () { ... } part (and all "this" instances) the code will work. Thanks in advance for any help.
The problem is the context inside the timer handler, the easiest fix here is to use a closure variable
$('.foo').each(function () {
var $this = $(this);
var updateChart = $this.peity('donut');
var text = "";
var i = 0;
function myLoop() {
setTimeout(function () {
text = i + "/12";
updateChart.text(text)
.change()
i = i + 0.2;
var maxValue = $this.data("value");
if (i <= maxValue) myLoop();
}, 0.5)
}
myLoop();
});
When the timeout callback is executed, the this context refer to window, because you are actually calling window.setTimeout method.
Try this:
$('.foo').each(function () {
var updateChart = $(this).peity('donut');
var text = "";
var i = 0;
function myLoop() {
setTimeout($.proxy(function () {
text = i + "/12";
updateChart.text(text)
.change()
i = i + 0.2;
var maxValue = $(this).data("value");
if (i <= maxValue) myLoop();
},this), 0.5)
}
myLoop();
});

plain javascript - increment number using function like $.animate with comma

I am developing a game that will animate the money that is added or subtracted.
The jquery solution is here:
How to increment number using animate with comma using jQuery?
How can I do this in plain javascript?
I want to avoid using jquery
In this solution, no jQuery is needed
var from=40000, to=50000;
function increment() {
setTimeout(function() {
from++;
if(from <= to) {
document.getElementById("test").innerHTML = from;
increment();
}
}, 10);
}
increment();
Please visit the jsfiddle. http://jsfiddle.net/TTaA4/
var counter = 0;
var timer = setInterval(function () {
if (counter >= 100 ) {
clearInterval(timer);
}
counter++;
// call numberWithCommas(counter) to get no.s with comma..
}, 100);
function numberWithCommas(x) {
return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}
the above code for comma function is shamelessly copied from https://stackoverflow.com/a/2901298/2466168
http://jsfiddle.net/2MwSv/
Try it out in your javascript console:
var a = 40000;
var b = 45000;
console.log(commaSeparateNumber(a));
function animate(opts) {
var start = new Date;
var id = setInterval(function () {
var timePassed = new Date - start
var progress = timePassed / opts.duration
if (progress > 1) progress = 1
var delta = progress;
opts.step(delta)
if (progress == 1) {
clearInterval(id)
}
}, opts.delay || 10)
}
function commaSeparateNumber(val) {
while (/(\d+)(\d{3})/.test(val.toString())) {
val = val.toString().replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");
}
return val;
}
animate({
delay: 10,
duration: 3000,
step: function (progress) {
var difference = b - a;
console.log(commaSeparateNumber(a + Math.round(progress * difference)));
}
});
Sources:
http://javascript.info/tutorial/animation
How to increment number using animate with comma using jQuery?

Extend Zepto.js with a jQuery method? scrollTop()

I'm using Zepto.js on a current project. Zepto doesn't support the scrollTop() method that jQuery has in it.
Is it possible to kind of extend Zepto to work with scrollTop() too?
Update: All I want is to create my own small and simple "animated scroll" function like I have used before with jQuery. See the working example here. However I have no idea how to make the same function work without the scrollTop() function available in Zepto.js.
scrollTop isn't animatable using Zepto's .animate method, as it uses CSS transitions.
Try something like this: http://jsfiddle.net/DVDLM/5/
function scroll(scrollTo, time) {
var scrollFrom = parseInt(document.body.scrollTop),
i = 0,
runEvery = 5; // run every 5ms
scrollTo = parseInt(scrollTo);
time /= runEvery;
var interval = setInterval(function () {
i++;
document.body.scrollTop = (scrollTo - scrollFrom) / time * i + scrollFrom;
if (i >= time) {
clearInterval(interval);
}
}, runEvery);
}
$('#trigger').click(function () {
scroll('600px', 500);
});
EDIT: I added a runEvery variable, which specifies how often the interval should be ran. The lower this is, the smoother the animation is, but it could affect performance.
EDIT2: I think I misread the question. Here is the answer to the new question:
$.zepto.scrollTop = function (pixels) {
this[0].scrollTop = pixels;
};
dont want to steel nobody work so here is the short answer
Porting from jQuery to Zepto
Use the DOM native scrollTop property:
$('#el')[0].scrollTop = 0;
(function ($) {
['width', 'height'].forEach(function(dimension) {
var offset, Dimension = dimension.replace(/./, function(m) { return m[0].toUpperCase() });
$.fn['outer' + Dimension] = function(margin) {
var elem = this;
if (elem) {
var size = elem[dimension]();
var sides = {'width': ['left', 'right'], 'height': ['top', 'bottom']};
sides[dimension].forEach(function(side) {
if (margin) size += parseInt(elem.css('margin-' + side), 10);
});
return size;
}
else {
return null;
}
};
});
["Left", "Top"].forEach(function(name, i) {
var method = "scroll" + name;
function isWindow( obj ) {
return obj && typeof obj === "object" && "setInterval" in obj;
}
function getWindow( elem ) {
return isWindow( elem ) ? elem : elem.nodeType === 9 ? elem.defaultView || elem.parentWindow : false;
}
$.fn[method] = function( val ) {
var elem, win;
if (val === undefined) {
elem = this[0];
if (!elem) {
return null;
}
win = getWindow(elem);
// Return the scroll offset
return win ? ("pageXOffset" in win) ? win[i ? "pageYOffset" : "pageXOffset"] :
win.document.documentElement[method] ||
win.document.body[method] :
elem[method];
}
// Set the scroll offset
this.each(function() {
win = getWindow(this);
if (win) {
var xCoord = !i ? val : $(win).scrollLeft();
var yCoord = i ? val : $(win).scrollTop();
win.scrollTo(xCoord, yCoord);
}
else {
this[method] = val;
}
});
}
});
})(Zepto);
The answer is simple, Zepto dose not use timeout style animation, it uses css3, so here is a basic implementation for a scroll function:
HTML:
Animated Scroll
Hello You
​
CSS:
#page { height:5000px; position:relative; }
#element { position:absolute; top:600px }
JS:
function scroll(selector, animate, viewOffset) {
$('body').scrollToBottom (600, '800');
}
$('#trigger').click(function(e) {
e.preventDefault();
scroll( $('#element'), true, 30 );
});
$.fn.scrollToBottom = function(scrollHeight ,duration) {
var $el = this;
var el = $el[0];
var startPosition = el.scrollTop;
var delta = scrollHeight - startPosition;
var startTime = Date.now();
function scroll() {
var fraction = Math.min(1, (Date.now() - startTime) / duration);
el.scrollTop = delta * fraction + startPosition;
if(fraction < 1) {
setTimeout(scroll, 10);
}
}
scroll();
};
​
Note that version 1.0 of Zeptos now supports scrollTop(). See Documentation:
http://zeptojs.com/#scrollTop

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