jQuery Menu how to contain submenus within Div - javascript

I am trying to create an 'application' contained in a div on a web page. This can't be any larger than certain dimensions (lets say: 550px by 280px). I have a menu with at least 1-3 sub menus for each item. The problem is, while I know the submenu is no larger than 280px high, the submenus often extend beyond the parent div's bounds (except for the last one which always grows upward not down).
Is there any way to make the menus grow up or down depending on whether it will extend beyond the div's bounds?
Here is a JSFiddle: http://jsfiddle.net/3FqcG/
Notice how the "Salzburg" submenu grows down beyond the bounds of the black DIV? I want that to grow up if it is too long and down if there is enough room.
Currently, I am just using the basic initialization: $( "#menu" ).menu();
Thanks!

I don't believe you can do this in CSS.
This leaves us with javascript. The basic idea is to:
calculate the baseline of the menu
if this lies outside the boundary
move the menu upwards to correct the position
live almost happily ever after
But, we have one major issue:
Though we capture the focus of an element, we don't know when its submenu is displayed & positioned. So although your problem is technically solved, it is by far not a desirable solution.
UPDATE
The best workaround I could come up with was to:
Turn off the animation (to avoid ugly glitches)
Add a watcher that would constantly monitor the element that is about to be opened
If opened, apply the position correction
Anyway, if you consider coming this far, you might as well override the default positioning of the jquery ui component, with the note that you will not be able to easily update the library. Update: or try Rudy Garcia's version if it works
Demo
Code of the demo:
var BASE_OFFSET = $('#menuContainer').offset().top;
var MAX_OFFSET = $('#menuContainer').height(); // get the offset of the container
var whenVisible = function($el, callback){ //executes callback when $el is visible
if($el.is(':visible')){ // if visible
callback(); // execute callback
}else{ // otherwise
setTimeout(function(){whenVisible($el, callback);},10); // do the same check in 10 ms
}
};
var fixPosition = function($menu){ // correct the position of the menu in respect to #menuContainer
var h = $menu.outerHeight(true); // take the height of the menu
var menuBottom = $menu.offset().top + h - BASE_OFFSET; // the baseline of the menu (taking into consideration the BASE_OFFSET)
if(menuBottom > MAX_OFFSET){ // if this is outside the MAX height
var diff = MAX_OFFSET - menuBottom; // calculate the difference
var newTop = $menu.position().top + diff; // modify current positioning with the calculated diff value
$menu.css('top', newTop + 'px'); // apply it to top (which is also used by jquery to position submenus
}
$.fx.off = false; // switch animations back on
};
$( "#menu" ).menu().on('menufocus', function(ev, ui){ // on the event menufocus
var $ui = $(ui.item); //take the focused element
var $menu = $ui.children('ul'); // take its related submenu
if($menu.length === 0){ // if there is none
return; // just terminate
}
$.fx.off = true; // switch off jQuery effects (otherwise you'll have glitches)
whenVisible($menu, function(){fixPosition($menu);}); // execute fixPosition when $menu is visible
});

You could also look at the API for this widget:
http://api.jqueryui.com/menu/
You can use the position option to position the elements how you want.
This will change the position so that they are within the box, however you will want to dynamically access the last to give it the position you want as the code below will change all menu items to move up 50.
$( "#menu" ).menu({ position: { my: "left top", at: "right+5 top-50" } });
A complete list of positioning options are also found here: http://api.jqueryui.com/position/
Apparently jquery UI has accounted for this and has given the option "within" to make sure your element stays within another element of your choice.
Therefore Your solution should be this:
$( "#menu" ).menu({ position: {within: '#menuContainer' } });

Related

Prevent viewport from moving when removing DOM elements

I'm trying to implement an HTML infinite scroller in which at any given time there are only a handful of div elements on list (to keep the memory footprint small).
I append a new div element to the list and at the same time I'm removing the first one, so the total count of divs remains the same.
Unfortunately the viewport doesn't stay still but instead it jumps backwards a little bit (the height of the removed div actually).
Is there a way to keep the viewport still while removing divs from the list?
I made a small self contained HTML page (well, it still needs JQuery 3.4.1) which exposes the problem: it starts by adding 5 divs and then it keeps adding a new one and removing the first one every 1 second
function getRandomColor() {
var letters = '0123456789ABCDEF';
var color = '#';
for (var i = 0; i < 6; i++) {
color += letters[Math.floor(Math.random() * 16)];
}
return color;
}
function removeit() {
// remove first one
var tiles = $(".tile");
$(tiles[0]).remove();
}
function addit() {
// append new one
var jqueryTextElem = $('<div class="tile" style="height:100px;background-color:' + getRandomColor() + '"></div>');
$("#inner-wrap").append(jqueryTextElem);
}
function loop() {
removeit();
addit();
window.setTimeout(loop, 1000);
}
addit();
addit();
addit();
addit();
addit();
loop();
<div id="inner-wrap"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
You can temporarily add position: fixed to the parent element:
first add position: fixed to the parent;
then remove the item;
then remove position: fixed from the parent
I have a feeling you're trying to have your cake and eat it, in that if you get the viewport to be "still", I think you're meaning you don't want a user to see the scrollbar move and then also not have any new affordance to scroll further down the page, because you would want the scrollbar thumb/grabber to still sit at the bottom of the scrollbar track?
I mean, you could just use $(window).scrollTop($(window).scrollTop() + 100); in your example to make it so the scroll position of the viewport won't visually move when removing elements, but at that point, you wouldn't be keeping the users view of the current elements the same or even allowing a user to have new content further down the page to scroll towards. You'd just be "pushing up" content through the view of the user?
If you are trying to lighten the load of what is currently parsed into document because you are doing some heavy lifting on the document object at runtime, maybe you still want to remove earlier elements, but retain their geometry with some empty sentinel element that always has the height of all previously removed elements added to it? This would allow you to both have a somewhat smaller footprint (though not layout-wise), while still having a usable scrollbar that can communicate to a user and both allow a user to scroll down, towards the content that has been added in.
All in all, I think what you currently have is how most infinite scrollers do and should work, meaning the scroll position and scrollbar should change when content is added in the direction the user is scrolling towards, this communicates to them that they can in fact keep scrolling that way. You really shouldn't want the viewports scroll position to be "still".
To see more clearly why I don't think you have an actual issue, replace your loop() definition with something like this...
function loop() {
$(window).scroll(function() {
// check for reaching bottom of scroller
if ($(window).scrollTop() == ($(document).height() - $(window).height())) {
addit();
removeit();
}
})
}

So DOM scrollIntoView aligns top/bottom, but what about left/right?

I would like to scroll horizontally the given element. The only way I find is using ScrollIntoView DOM method, which allows either align the element's bottom with the view bottom or the top - with the view top.
But what if the element is OK with respect to the Y axis, and I only want to scroll it horizontally? How can I align its left with the view left or its right with the view right?
EDIT
Here is more context. I have a YUI table with a horizontal scrollbar. I wish to scroll it programmatically to a certain TD node. I do not think window.scrollTo is of any help to me, since the scrollbar is on a div element, not on the whole page.
EDIT2
Turns out there is a duplicate SO question with the right answer - How can I scroll programmatically a div with its own scrollbars?
Voting to close mine.
I've recently had a problem with a table header that had inputs as filters for each column. Tabbing through the filters would move the focus, but if one of the inputs wasn't visible or if it was partly visible, it would only JUST bring the input into view, and I was asked to bring the full input and column into view. And then I was asked to do the same if tabbing backwards to the left.
This link helped to get me started: http://www.webdeveloper.com/forum/showthread.php?197612-scrollIntoView-horizontal
The short answer is that you want to use:
document.getElementById('myElement').scrollLeft = 50;
or:
$('#myElement')[0].scrollLeft = 50;
Here's my solution (which may be overkill for this question, but maybe it'll help someone):
// I used $.on() because the table was re-created every time the data was refreshed
// #tableWrapper is the div that limits the size of the viewable table
// don't ask me why I had to move the head head AND the body, they were in 2 different tables & divs, I didn't make the page
$('#someParentDiv').on('focus', '#tableWrapper input', function () {
var tableWidth = $('#tableWrapper')[0].offsetWidth;
var cellOffset = $(this).parent()[0].offsetLeft;
var cellWidth = $(this).parent()[0].offsetWidth;
var cellTotalOffset = cellOffset + cellWidth;
// if cell is cut off on the right
if (cellTotalOffset > tableWidth) {
var difference = cellTotalOffset - tableWidth;
$('#tableWrapper').find('.dataTables_scrollHead')[0].scrollLeft = difference;
$('#tableWrapper').find('.dataTables_scrollBody')[0].scrollLeft = difference;
}
// if cell is cut off on the left
else if ($('#tableWrapper').find('.dataTables_scrollHead')[0].scrollLeft > cellOffset) {
$('#tableWrapper').find('.dataTables_scrollHead')[0].scrollLeft = cellOffset;
$('#tableWrapper').find('.dataTables_scrollBody')[0].scrollLeft = cellOffset;
}
});
This is something I used a while back. There might be better and more efficient way of doing it but this gets the work done:
$(".item").click(function(event){
event.preventDefault();
// I broke it down into variable to make it easier to read
var tgt_full = this.href,
parts = tgt_full.split("#"),
tgt_clean = parts[1],
tgt_offset = $("#"+tgt_clean).offset(),
tgt_left = tgt_offset.left;
$('html, body').animate({scrollLeft:tgt_left}, 1000, "easeInOutExpo");
})
You just need to make sure that the item is an a tag with an href that corresponds to the target id element:
HTML:
go to section 1
...
<section id="one"> Section 1</section>
Hope this helps!

How to hide a button that is affixed when it 'floats' over a DIV?

I have a button back-to-top that is affixed to the left side of the screen - it uses scrollTop to slide-scroll to the top of the page when it's clicked. When the page the loads, the button is visible and does not cover anything that is readable etc.
When a user scrolls down the page, the button goes over certain DIVs that have text content. When the button goes into such a DIV I want it to hide using .hide(). Can't get it to work, here's what I have:
var p = $('a.back-to-top');
var position = p.position();
if(position == $('#about-me')){
$('a.back-to-top').hide();
}
Is if(position == $('#about-me')) the correct way to check if the button's position is in the #about-me DIV? Or, should I create a variable similar to position for the DIV?
EDIT: A messy but simple fiddle
You will need to do this check inside of a callback .. probably $(window).scroll so that it is checked each time the window scrolls; otherwise, it is only checked when the page loads.
I don't think you want to use position either as that is position relative to parent. Instead, you probably want .offset. This returns an object with top and left members. An == comparison does not make sense, especially to a jQuery object. You want to use:
$(window).on('scroll', function () {
var offset = $("a.back-to-top").offset().top;
var within = $("#about-me").offset().top;
if (offset >= within && offset <= within + $("#about-me").height()) {
$("a.back-to-top").hide();
}
else {
$("a.back-to-top").show();
}
});​
The offset of .back-to-top changes with scrolling if it has a fixed position, but the offset of the static block does not change, so you can do this comparison.
See it in action: http://jsfiddle.net/QnhgF/
http://api.jquery.com/position/ - position() method returns a position object which has .left and .top properties. So basically, you can't compare position to some object returned by a selector. Instead, you should compare the "top" property values of both elements.
For example you have:
var p = $('a.back-to-top');
var position = p.position();
Also get this:
var aboutMePosition = $('#about-me').position();
And then you can compare:
aboutMePosition.top and position.top whichever way you need.

javascript bind an event handler to horizontal scroll

Is there a way in javascript to bind an event handler to a horizontal scroll as opposed to the generic scroll event which is fired when the user scrolls horizontally and vertically? I want to trigger an event only when the user scrolls horizontally.
I searched around for an answer to this question, but couldn't seem to find anything.
Thanks!
P.S. My apologies if I'm using some terminology incorrectly. I'm fairly new to javascript.
UPDATE
Thanks so much for all your answers! In summary, it looks like you are all saying that this isn't supported in javascript, but I that I can accomplish the functionality with something like this (using jQuery) (jsFiddle):
var oldScrollTop = $(window).scrollTop();
$(window).bind('scroll', function () {
if (oldScrollTop == $(window).scrollTop())
//scrolled horizontally
else {
//scrolled vertically
oldScrollTop = $(window).scrollTop();
}
});​
That's all I needed to know. Thanks again!
Answering from my phone, so unable to provide code at the moment.
What you'll need to do is subscribe to the scroll event. There isn't a specific one for vertical/horizontal.
Next, you'll need to get some measurements about the current display area. You'll need to measure the window.clientHeight and window.clientWidth.
Next, get window.top and window.left. This will tell you where position of the viewport is, ie if it's greater than 0 then scroll bars have been used.
It's pretty simple math from here to get what you need. If no one else has provided a code example in the next few hours I'll try to do so.
Edit:
A bit further information.
You must capture the scroll event. You also need to store the initial window.top and window.left properties somewhere. Whenever the scroll event happens, do a simple check to see if the current top/left values differ from the stores value.
At this point, if either are different you can trigger your own custom events to indicate vertical or horizontal scrolling. If you are using jQuery, this is very easy. If you are writing js without library assistance, it's easy too but a little more involved.
Do some searches for event dispatching in js.
You can then write any other code you want to subscribe to your custom events without needing to tie them together with method calls.
I wrote a jQuery plugin for you that lets you attach functions to the scrollh event.
See it in action at jsfiddle.net.
/* Enable "scrollh" event jQuery plugin */
(function ($) {
$.fn.enableHScroll = function() {
function handler(el) {
var lastPos = el
.on('scroll', function() {
var newPos = $(this).scrollLeft();
if (newPos !== lastPos) {
$(this).trigger('scrollh', newPos - lastPos);
lastPos = newPos;
}
})
.scrollLeft();
}
return this.each(function() {
var el = $(this);
if (!el.data('hScrollEnabled')) {
el.data('hScrollEnabled', true);
handler(el);
}
});
}
}(jQuery));
It's this easy to use:
$('#container')
.enableHScroll()
.on('scrollh', function(obj, offset) {
$('#info').val(offset);
});
Please note that scroll events come very fast. Even if you click in the scrollbar to jump to a new position, many scroll events are generated. You may want to adjust this code to wait a short time and accumulate all the changes in position during that time before firing the hscroll event.
You can use the same scroll event, but within your handler use the scrollLeft function to see if the scrollbar moved horizontally from the last time the event was fired. If the scrollbar did not move then just return from your handler. Otherwise update your variable to the new position and take action.
You can check if the the x value of the page changes and ignore your y value.
If the x value changes: There is your horizontal scroll.
With page-load, store the initial scrollbar positions for both in two variables (presumably both will be 0). Next, whenever a scroll event occurs, find the scrollleft and scrolltop properties. If the scrollleft property's value is different and scrolltop's value is same as compared to their earlier values, that's a horizontal scroll. Then set the values of the variables to the new scroll values.
No, there is no special event for scroll horizontal (it is for global scroll), but you can try to check the position of content by property .scrollLeft and if it's different from the previous value it means that the user scrolled content horizontally.

Scroll a div vertically to a desired position using jQuery

This is a followup question for this:
Scrollpane on the bottom, css is hacky, javascript is hard
I ended up doing the scrolling in the same way explained in the accepted answer.
Now there is a request that one item is selected somehow (eg. as an url parameter or by some javascript calls) I should scroll the pane to the item with the corresponding ID in the scrollpane. Like a link to an anchor () would work!
I want to make a javascript call like this
function scrollTo(id) {
$('#middle').magicallyScrollThatItemWouldBeVisible(itemid);
}
But this is not in jQuery (or at least I don't know of it). So is there a way to make it?
I'll post a simple jsFiddle here:
http://jsfiddle.net/ruisoftware/U6QdQ/4/
Help me write that scrollTo function!
A .animate would be fine too.
UPDATE: If it was not clear I would like it to only align to the left or right side of the panel, it it was overflowed on that side (so the minimum possible amount of scrolling happens)
It's not jQuery, just JavaScript, and I've actually never used it all, so I'm not sure how you would have to mess with it to get it to work in this situation, but there is a scrollIntoView function:
yourElement.scrollIntoView();
Since the elements have a fixed width, you can count the number of elements by using .index() + 1, and animate to this value (after subtracting the container's width).
If you want the element to be centered, use - Math.round(middle.width()/100)*50.
Fiddle: http://jsfiddle.net/U6QdQ/17/
//This code should be run on load / DOMReady
(function($){ //Run on load / DOMReady
$.fn.magicScrollTo = function(){
var middle = $("#middle");
var currentScrollLeft = middle.scrollLeft();
var width = middle.width();
var newScrollLeft = this.offset().left + currentScrollLeft - middle.offset().left;
if(newScrollLeft >= currentScrollLeft && newScrollLeft <= currentScrollLeft + width - this.outerWidth()) return;
if(newScrollLeft > currentScrollLeft){ //If the element is at the right side
newScrollLeft = newScrollLeft - width + this.outerWidth();
}
middle.animate({
scrollLeft: newScrollLeft,
}, 'fast')
}
})(jQuery);
Usage:
//Select the 4rd element, and scroll to it (eq is zero-based):
$('.item').eq(3).magicScrollTo();
Something along these lines would be a good start:
http://jsfiddle.net/vHjJ4/
This will bring the target into the centre of the carousel. I think you will have to add in some extra checks to make sure that it didn't scroll to far, for example if you targeted the first or last element...unless this is built into the scroll function (it might be).
I'm not sure I understand your question exactly, but it sounds like you're asking how to scroll horizontally to the selected item in the bottom pane. If so, try something like this:
//get the position of the element relative to the parent ("middle")
var pos = $("#itemid").position();
if (pos){
$("#middle").scrollLeft(pos.left);
}
From here, you can use the width of middle to center the item if needed.

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