Develop Reference

How to fill progress bar based on number of letters typed?

I am trying to make an input box that has a div on the bottom which will act sort of a progress bar to tell you when you have enough characters typed.
I can't get this animation to work, even though I thought it would be a lot easier when I decided to try this project.
Please let me know what is wrong with my code. Thanks!
<div id='cntnr'>
<div id='inptDiv'>
<input id='inpt1'>
<div id='prgInd'></div>
</div>
</div>
var main = function() {
var inptAmnt = document.getElementById('inpt1').value;
if(inptAmnt.length === 1) {
$('#prgInd').css('width', 25);
}
}
$(document).ready(main);
I also tried this code first but it didn't work either:
var main = function() {
var inptAmnt = document.getElementById('inpt1').value;
if(inptAmnt.length === 1) {
$('#prgInd').animate({
width:25
},200 )
}
}
$(document).ready(main);
JSFiddle: https://jsfiddle.net/qcsb53ha/

You can use jQuery to listen to the change, keyup and paste events of your text input.
Then, work out a percentage, based on your desired input length; and use this percentage to set the width of the progress bar.
If the "percentage" is above 100 - just reset it to 100 again. jQuery code is below:
var desiredLength = 4; // no jokes please...
// Listen to the change, keyup & paste events.
$('#text-box').on('change keyup paste', function() {
// Figure out the length of the input value
var textLength = $('#text-box').val().length;
// Calculate the percentage
var percent = (textLength / desiredLength) * 100;
// Limit the percentage to 100.
if (percent > 100) {
percent = 100;
}
// Animate the width of the bar based on the percentage.
$('.progress-bar').animate({
width: percent + '%'
}, 200)
});
See the working JSFiddle here : https://jsfiddle.net/jqbka5j8/1/
I've included normal code for setting the width, and the code for animating the width. You can comment/uncomment the necessary ones and test appropriately.
Hope this helps!

There's no need the use of javascript, you can use only pure CSS and Content Editable:
HTML
<div>
<span contenteditable="true">sdfsd</span>
</div>
CSS
span
{
border: solid 1px black;
}
div
{
max-width: 200px;
}
JsFiddle example

Do not execute jQuery script if CSS is of particular value

On my website, I have a sidebar DIV on the left and a text DIV on the right. I wanted to make the sidebar follow the reader as he or she scrolls down so I DuckDuckGo'ed a bit and found this then modified it slightly to my needs:
<script type='text/javascript'>//<![CDATA[
$(window).load(function(){
$(function(){
var $sidebar = $('#sidebar'),
sidebarOffset = $sidebar.offset(),
$window = $(window),
gap = $('#header').css('marginBottom').replace(/[^-\d\.]/g, ''),
distance = ($window.scrollTop()) - (sidebarOffset.top - gap),
footerHeight = $('#footer').outerHeight();
$window.scroll(function(){
distance = ($window.scrollTop()) - (sidebarOffset.top - gap);
if ( distance > 0 ) {
$sidebar.css({'top': gap + 'px', 'position' : 'fixed'});
} else {
$sidebar.css({'top': '0', 'position': 'relative'});
}
})
});
});//]]>
</script>
And it works just like I want it to. However, my website uses Skeleton framework to handle responsive design. I've designed it so that when it goes down to mobile devices (horizontal then vertical), sidebar moves from being to the left of the text to being above it so that text DIV can take 100% width. As you can probably imagine, this script causes the sidebar to cover parts of text as you scroll down.
I am completely new to jQuery and I am doing my best through trial-and-error but I've given up. What I need help with is to make this script not execute if a certain DIV has a certain CSS value (i.e. #header-logo is display: none).
Ideally, the script should check for this when user resizes the browser, not on website load, in case user resizes the browser window from normal size to mobile size.
I imagine it should be enough to wrap it in some IF-ELSE statement but I am starting to pull the hair out of my head by now. And since I don't have too much hair anyway, I need help!
Thanks a lot in advance!

This function will execute on window resize and will check if #header-logo is visible.
$(window).resize(function() {
if ($('#header-logo').is(':visible')) {
// Your code
}
});
I think you need to check this on load to, because you don't know if the user will start with mobile view or not. You could do something like this:
$(window).resize(function() {
if ($('#header-logo').is(':visible')) {
// Your code
}
}).resize();
This will get executed on load and on resize.
EDIT: You will probably need to turn off the scroll function if #header-logo is not visible. So, instead of create the function inside the scroll event, you need to create it outside:
$(window).resize(function() {
if ($('#header-logo').is(':visible')) {
var $sidebar = $('#sidebar'),
sidebarOffset = $sidebar.offset(),
$window = $(window),
gap = $('#header').css('marginBottom').replace(/[^-\d\.]/g, ''),
distance = ($window.scrollTop()) - (sidebarOffset.top - gap),
footerHeight = $('#footer').outerHeight();
function myScroll() {
distance = ($window.scrollTop()) - (sidebarOffset.top - gap);
if ( distance > 0 ) {
$sidebar.css({'top': gap + 'px', 'position' : 'fixed'});
} else {
$sidebar.css({'top': '0', 'position': 'relative'});
}
}
$window.on('scroll', myScroll);
} else {
$(window).off('scroll', myScroll);
}
});
Didn't test it, but you get the idea.

$("#headerLogo").css("display") will get you the value.
http://api.jquery.com/css/
I also see you only want this to happen on resize, so wrap it in jquery's resize() function:
https://api.jquery.com/resize/

Synchronized scrolling using jQuery?

I am trying to implement synchronized scrolling for two DIV with the following code.
DEMO
$(document).ready(function() {
$("#div1").scroll(function () {
$("#div2").scrollTop($("#div1").scrollTop());
});
$("#div2").scroll(function () {
$("#div1").scrollTop($("#div2").scrollTop());
});
});
#div1 and #div2 is having the very same content but different sizes, say
#div1 {
height : 800px;
width: 600px;
}
#div1 {
height : 400px;
width: 200px;
}
With this code, I am facing two issues.
1) Scrolling is not well synchronized, since the divs are of different sizes. I know, this is because, I am directly setting the scrollTop value. I need to find the percentage of scrolled content and calculate corresponding scrollTop value for the other div. I am not sure, how to find the actual height and current scroll position.
2) This issue is only found in firefox. In firefox, scrolling is not smooth as in other browsers. I think this because the above code is creating a infinite loop of scroll events.
I am not sure, why this is only happening with firefox. Is there any way to find the source of scroll event, so that I can resolve this issue.
Any help would be greatly appreciated.

You can use element.scrollTop / (element.scrollHeight - element.offsetHeight) to get the percentage (it'll be a value between 0 and 1). So you can multiply the other element's (.scrollHeight - .offsetHeight) by this value for proportional scrolling.
To avoid triggering the listeners in a loop you could temporarily unbind the listener, set the scrollTop and rebind again.
var $divs = $('#div1, #div2');
var sync = function(e){
var $other = $divs.not(this).off('scroll'), other = $other.get(0);
var percentage = this.scrollTop / (this.scrollHeight - this.offsetHeight);
other.scrollTop = percentage * (other.scrollHeight - other.offsetHeight);
// Firefox workaround. Rebinding without delay isn't enough.
setTimeout( function(){ $other.on('scroll', sync ); },10);
}
$divs.on( 'scroll', sync);
http://jsfiddle.net/b75KZ/5/

Runs like clockwork (see DEMO)
$(document).ready(function(){
var master = "div1"; // this is id div
var slave = "div2"; // this is other id div
var master_tmp;
var slave_tmp;
var timer;
var sync = function ()
{
if($(this).attr('id') == slave)
{
master_tmp = master;
slave_tmp = slave;
master = slave;
slave = master_tmp;
}
$("#" + slave).unbind("scroll");
var percentage = this.scrollTop / (this.scrollHeight - this.offsetHeight);
var x = percentage * ($("#" + slave).get(0).scrollHeight - $("#" + slave).get(0).offsetHeight);
$("#" + slave).scrollTop(x);
if(typeof(timer) !== 'undefind')
clearTimeout(timer);
timer = setTimeout(function(){ $("#" + slave).scroll(sync) }, 200)
}
$('#' + master + ', #' + slave).scroll(sync);
});

This is what I'm using. Just call the syncScroll(...) function with the two elements you want to synchronize. I found pawel's solution had issues with continuing to slowly scroll after the mouse or trackpad was actually done with the operation.
See working example here.
// Sync up our elements.
syncScroll($('.scroll-elem-1'), $('.scroll-elem-2'));
/***
* Synchronize Scroll
* Synchronizes the vertical scrolling of two elements.
* The elements can have different content heights.
*
* #param $el1 {Object}
* Native DOM element or jQuery selector.
* First element to sync.
* #param $el2 {Object}
* Native DOM element or jQuery selector.
* Second element to sync.
*/
function syncScroll(el1, el2) {
var $el1 = $(el1);
var $el2 = $(el2);
// Lets us know when a scroll is organic
// or forced from the synced element.
var forcedScroll = false;
// Catch our elements' scroll events and
// syncronize the related element.
$el1.scroll(function() { performScroll($el1, $el2); });
$el2.scroll(function() { performScroll($el2, $el1); });
// Perform the scroll of the synced element
// based on the scrolled element.
function performScroll($scrolled, $toScroll) {
if (forcedScroll) return (forcedScroll = false);
var percent = ($scrolled.scrollTop() /
($scrolled[0].scrollHeight - $scrolled.outerHeight())) * 100;
setScrollTopFromPercent($toScroll, percent);
}
// Scroll to a position in the given
// element based on a percent.
function setScrollTopFromPercent($el, percent) {
var scrollTopPos = (percent / 100) *
($el[0].scrollHeight - $el.outerHeight());
forcedScroll = true;
$el.scrollTop(scrollTopPos);
}
}

If the divs are of equal sizes then this code below is a simple way to scroll them synchronously:
scroll_all_blocks: function(e) {
var scrollLeft = $(e.target)[0].scrollLeft;
var len = $('.scroll_class').length;
for (var i = 0; i < len; i++)
{
$('.scroll_class')[i].scrollLeft = scrollLeft;
}
}
Here im using horizontal scroll, but you can use scrollTop here instead. This function is call on scroll event on the div, so the e will have access to the event object.
Secondly, you can simply have the ratio of corresponding sizes of the divs calculated to apply in this line $('.scroll_class')[i].scrollLeft = scrollLeft;

I solved the sync scrolling loop problem by setting the scroll percentage to fixed-point notation: percent.toFixed(0), with 0 as the parameter. This prevents mismatched fractional scrolling heights between the two synced elements, which are constantly trying to "catch up" with each other. This code will let them catch up after at most a single extra step (i.e., the second element may continue to scroll an extra pixel after the user stops scrolling). Not a perfect solution or the most sophisticated, but certainly the simplest I could find.
var left = document.getElementById('left');
var right = document.getElementById('right');
var el2;
var percentage = function(el) { return (el.scrollTop / (el.scrollHeight - el.offsetHeight)) };
function syncScroll(el1) {
el1.getAttribute('id') === 'left' ? el2 = right : el2 = left;
el2.scrollTo( 0, (percentage(el1) * (el2.scrollHeight - el2.offsetHeight)).toFixed(0) ); // toFixed(0) prevents scrolling feedback loop
}
document.getElementById('left').addEventListener('scroll',function() {
syncScroll(this);
});
document.getElementById('right').addEventListener('scroll',function() {
syncScroll(this);
});

I like pawel's clean solution but it lacks something I need and has a strange scrolling bug where it continues to scroll and my plugin will work on multiple containers not just two.
http://www.xtf.dk/2015/12/jquery-plugin-synchronize-scroll.html
Example & demo: http://trunk.xtf.dk/Project/ScrollSync/
Plugin: http://trunk.xtf.dk/Project/ScrollSync/jquery.scrollSync.js
$('.scrollable').scrollSync();

If you don't want proportional scrolling, but rather to scroll an equal amount of pixels on each field, you could add the value of change to the current value of the field you're binding the scroll-event to.
Let's say that #left is the small field, and #right is the bigger field.
var oldRst = 0;
$('#right').on('scroll', function () {
l = $('#left');
var lst = l.scrollTop();
var rst = $(this).scrollTop();
l.scrollTop(lst+(rst-oldRst)); // <-- like this
oldRst = rst;
});
https://jsfiddle.net/vuvgc0a8/1/
By adding the value of change, and not just setting it equal to #right's scrollTop(), you can scroll up or down in the small field, regardless of its scrollTop() being less than the bigger field. An example of this is a user page on Facebook.
This is what I needed when I came here, so I thought I'd share.

From the pawel solution (first answer).
For the horizzontal synchronized scrolling using jQuery this is the solution:
var $divs = $('#div1, #div2'); //only 2 divs
var sync = function(e){
var $other = $divs.not(this).off('scroll');
var other = $other.get(0);
var percentage = this.scrollLeft / (this.scrollWidth - this.offsetWidth);
other.scrollLeft = percentage * (other.scrollWidth - other.offsetWidth);
setTimeout( function(){ $other.on('scroll', sync ); },10);
}
$divs.on('scroll', sync);
JSFiddle
An other solution for multiple horizontally synchronized divs is this, but it works for divs with same width.
var $divs = $('#div1, #div2, #div3'); //multiple divs
var sync = function (e) {
var me = $(this);
var $other = $divs.not(me).off('scroll');
$divs.not(me).each(function (index) {
$(this).scrollLeft(me.scrollLeft());
});
setTimeout(function () {
$other.on('scroll', sync);
}, 10);
}
$divs.on('scroll', sync);
NB: Only for divs with same width
JSFiddle

Getting Coordinates of an element on page scroll

I am having this problem where i have a set of 6 UL's having a common class x.Each of them consist of a specific section of the page.Now i have 6 menus that are related to each of the section.What i have to do is highlight the menu when its related section is in users view.
For this i thought that may be jQuery position(); or offset(); could have helped but they give the top and left of the element.I also tried using jQuery viewport plugin but apparently view port is big it can show more than one UL at a time hence i cant apply element specific logic here.I am not familliar to this but does anything changes of an element on scrolling?If yes then how to access it?
Please share your views.
Regards
Himanshu Sharma.

Is very easy to do it using jQuery and a dummy fixed HTML block that helps you find the current position of the viewport.
$(window).on("scroll load",function(){
var once = true;
$(".title").each(function(ele, index){
if($(this).offset().top > $("#viewport_helper").offset().top && once){
var index = $(this).index(".title");
$(".current").removeClass('current')
$("#menu li").eq(index).addClass('current')
once = false;
}
});
})
Check out a working example: http://jsfiddle.net/6c8Az/1/
You could also do something similar with the jQuery plugin, together with the :first selector:
$(window).on("scroll load",function(){
$(".title:in-viewport:first").each(function(){
var index = $(this).index(".title");
$(".current").removeClass('current')
$("#menu li").eq(index).addClass('current')
});
})

You can get the viewport's width and height via $(document).width() and $(document).height()
You can get how many pixels user scrolls via $(document).scrollTop() and $(document).scrollLeft
Combining 1 and 2, you can calculate where the viewport rectangle is
You can get the rectangle of an element using $(element).offset(), $(element).width() and $(element).height()
So the only thing left to you is to determine whether the viewport's rectangle contains (or interacts) the elements's rectangle
So the whole code may look like:
/**
* Check wether outer contains inner
* You can change this logic to matches what you need
*/
function rectContains(outer, inner) {
return outer.top <= inner.top &&
outer.bottom >= inner.bottom &&
outer.left <= inner.left &&
outer.right >= inner.right;
}
/**
* Use this function to find the menu related to <ul> element
*/
function findRelatedMenu(element) {
return $('#menu-' + element.attr('id'));
}
function whenScroll() {
var doc = $(document);
var elem = $(element);
var viewportRect = {
top: doc.scrollTop(),
left: doc.scrollLeft(),
width: doc.width(),
height: doc.height()
};
viewportRect.bottom = viewportRect.top + viewportRect.height;
viewportRect.right = viewportRect.left + viewportRect.width;
var elements = $('ul.your-class');
for (var i = 0; i < elements.length; i++) {
var elem = $(elements[i]);
var elementRect = {
top: elem.offset().top,
left: elem.offset().left,
width: elem.width(),
height: elem.height()
};
elementRect.bottom = elementRect.top + elementRect.height;
elementRect.right = elementRect.left + elementRect.width;
if (rectContains(viewportRect, elementRect)) {
findRelatedMenu(elem).addClass('highlight');
}
}
}
$(window).on('scroll', whenScroll);

Let's see if i understood well. You have a page long enough to scroll, and there is an element that when it appears in the viewport, you wanna do something with it. So the only event that's is triggered for sure on the time the element gets in the viewport is the 'scroll'. So if the element is on the page and the scroll is on the viewport, what you need to do is bind an action to the scroll event to check if the element is in the view each time the event is trigger. Pretty much like this:
$(window).scroll(function() {
check_element_position();
});
Now, in order for you to know if the element is in the viewport, you need 3 things. The offset top of that element, the size of the viewport and the scroll top of the window. Should pretty much look like this:
function check_element_position() {
var win = $(window);
var window_height = win.height();
var element = $(your_element);
var elem_offset_top = element.offset().top;
var elem_height = element.height();
var win_scroll = win.scrollTop();
var pseudo_offset = (elem_offset_top - win_scroll);
if (pseudo_offset < window_height && pseudo_offset >= 0) {
// element in view
}
else {
// elem not in view
}
}
Here, (elem_offset_top - win_scroll) represent the element position if there was no scroll. Like this, you just have to check if the element offset top is higher then the window viewport to see if it's in view or not.
Finally, you could be more precise on you calculations by adding the element height (variable already in there) because the code i just did will fire the event even if the element is visible by only 1 pixels.
Note: I just did that in five minutes so you might have to fix some of this, but this gives you a pretty darn good idea of what's going on ;)
Feel free to comment and ask questions

How to let resize vertically a DIV with only jQuery - no plugins?

Edit: I put this snippet of code in jsbin: http://jsbin.com/eneru
I am trying to let the user resize (only vertically) a DIV element with jQuery. I read about jQuery UI, I tried it, and in some minutes, I had it working. But the library is adding a ~25KB overhead that I would like to avoid, since I only want simple vertical resizing.
So I tried to do it on my own. Here it is the HTML, I am using inline styling for clarity:
<div id="frame" style="border: 1px solid green; height: 350px">
<div style="height: 100%">Lorem ipsum blah blah</div>
<span id="frame-grip" style="display: block; width: 100%; height: 16px; background: gray"></span>
</div>
As you can see, there is a little bar under the DIV element, so the user can drag it up or down to resize the DIV. Here it is the Javascript code (using jQuery):
$(document).ready(function(){
var resizing = false;
var frame = $("#frame");
var origHeightFrame = frame.height();
var origPosYGrip = $("#frame-grip").offset().top;
var gripHeight = $("#frame-grip").height();
$("#frame-grip").mouseup(function(e) {
resizing = false;
});
$("#frame-grip").mousedown(function(e) {
resizing = true;
});
$("#frame-grip").mousemove(function(e) {
if(resizing) {
frame.height(e.pageY - origPosYGrip + origHeightFrame - gripHeight/2);
}
});
});
It works, more or less, but if you drag the bar too fast, it stops following the mouse movement and everything breaks.
It is the first time I try to do something serious (ahem) with JS and jQuery, so I may be doing something dumb. If so, please do tell me :)

You are doing something dumb: You're trying to do it yourself.
Hear me out, hear me out: Javascript across browsers is a horrible, horrible thing. There are many engines in many versions with many different operating systems, all of which have many subtleties, all of which make Javascript pretty much hell to work with. There is a perfectly good reason why librabries such as jQuery (and their extensions) have exploded in popularity: a lot of great programmers have spent a lot of hours abstracting all these horrible inconsistencies away so we don't have to worry about it.
Now, I am not sure about your user base, maybe you are catering to old housewives that still have dialup. But for the most part in this day and age the 25KB hit on the initial page load (as it will be cached afterwards) for the peace of mind that this is going to work in all browsers consistently is a small price to pay. There is no such thing as "simple" resizing when it comes to Javascript, so you're better off using UI.

I worked on a similar thing and managed to get it to work with maximum and minimum height and to me seems to work very fluid, this was my code.
$(document).ready(function()
{
var resizing = false;
var frame = $("#frame").height();
$(document).mouseup(function(event)
{
resizing = false;
frame = $("#frame").height();
});
$("#frame-grip").mousedown(function(event)
{
resizing = event.pageY;
});
$(document).mousemove(function(event)
{
if (resizing)
{
$("#frame").height(frame + resizing - event.pageY);
}
});
});
live example of how I used it, pull the red button, lacked images so i replaced with simple color. http://jsbin.com/ufuqo/23

I agree with Paolo about using UI, but here are some modifications to your code to get it working:
$(document).ready(function(){
var resizing = false;
var frame = $("#frame");
$(document).mouseup(function(e) {
resizing = false;
});
$("#frame-grip").mousedown(function(e) {
e.preventDefault();
resizing = true;
});
$(document).mousemove(function(e) {
if(resizing) {
var origHeightFrame = frame.height();
var origPosYGrip = $("#frame-grip").offset().top;
var gripHeight = $("#frame-grip").height();
frame.height(e.pageY - origPosYGrip + origHeightFrame - gripHeight/2);
}
});
});

You can save having a do-nothing handler called when you're not resizing, by only binding the mousemove function when you are actually dragging:
$(document).ready(function(){
var resizing = function(e) {
var frame = $("#frame");
var origHeightFrame = frame.height();
var origPosYGrip = $("#frame-grip").offset().top;
var gripHeight = $("#frame-grip").height();
frame.height(e.pageY - origPosYGrip + origHeightFrame - gripHeight/2);
return false;
}
var stopResizing = function(e) {
$(document).unbind("mouseover", resizing);
}
$("#frame-grip").mouseup(stopResizing);
$("#frame-grip").mousedown(function(e) {
e.preventDefault();
$(document).bind("mouseover", resizing).mouseup(stopResizing);
});
});
(sample at http://jsbin.com/ufuqo)