I'm trying to create a file listing a la windows explorer in HTML/Javascript. As such, I'd like the first row of the table, which contains the headings for all the columns, to be visible even when the columns are scrolled.
I've tried a few options involving placing the headings in a separate table, but all have failed for primarily one reason - when the file list is scrolled horizontally, the headings table does not scroll with it.
Hence, I'm essentially looking for an element linked to another in such a way that it scrolls with the other horizontally, but not vertically.
I realize many will think I should be using css and not tables, but this is moot as even using css I can't solve the problem of wanting the header bar to scroll with the files horizontally, but not vertically.
Any help you can offer would be greatly appreciated.
My suggestion is to use Javascript. Hook to the onScroll event of both scrollable elements, and on the event update the scrollLeft property of both elements.
var tableHeader = document.getElementById('tableHeader');
var tableBody = document.getElementById('tableBody');
function updateTableBody(e){
tableBody = tableHeader.scrollLeft;
}
function updateTableHeader(e){
tableHeader = tableBody.scrollLeft;
}
tableHeader.addEventListener('scroll', updateTableBody, false);
tableBody.addEventListener('scroll', updateTableHeader, false);
Of course, this is not bulletproof and could be optimized, but it will give you and idea and hopefully a good start.
NOTE: Make sure both element have the same dimensions, otherwise, the scroll will have a weird offset.
Unfortunately, this isn't available as a CSS-only solution. CSS has some features that theoretically should be capable of being used to scroll a TBODY, but browser support is far too inconsistent.
One solution not mentioned yet is the Ext JS library. It does a LOT more than just scrolled tables, and you'll have to review the licensing to see if it will work for you, but their grid object is the most robust rich-UI-like table replacement I've seen.
Related
I have a question on a big # of dom elmenets and performance.
Let's say I have 6000 dom elements on a page and the number of the elements can be increased as a user interact with the page (user scrolls to create a new dom element) like twitter.
To improve the performance of the page, I can think of only two things.
set display to none to invisible items to avoid reflow
remove invisible items from the dom then re-add them as needed.
Are they any other ways of improving a page with a lot of dom elements?
We had to deal with a similar problem on FoldingText. As the document grew larger, more line elements and associated span elements were created. The browser engine just seemed to choke, and so a better solution needed to be found.
Here's what we did, may or may not be useful for your purposes:
Visualize the entire page as a long document, and the browser viewport as the lens for a specific part of the long document. You really only have to show the part within the lens.
So the first part is to calculate the visible view port. (This depends on how your elements are placed, absolute / fixed / default)
var top = document.scrollTop;
var width = window.innerWidth;
var height = window.innerHeight;
Some more resources to find a more cross-browser based viewport:
How to get the browser viewport dimensions?
Cross-browser method for detecting the scrollTop of the browser window
Second, you need a data structure to know which elements are visible in that area
We already had a balanced binary search tree in place for text editing, so we extended it to manage line heights too, so this part for us was relatively easy. I don't think you'll need a complex data structure for managing your element heights; a simple array or object might do fine. Just make sure you can query heights and dimensions easily on it. Now, how would you get the height data for all your elements. A very simple (but computationally expensive for large amounts of elements!)
var boundingRect = element.getBoundingClientRect()
I'm talking in terms of pure javascript, but if you're using jQuery $.offset, $.position, and methods listed here would be quite helpful.
Again, using a data structure is important only as a cache, but if you want, you could do it on the fly (though as I've stated these operations are expensive). Also, beware of changing css styles and calling these methods. These functions force redraw, so you'll see a performance issue.
Lastly, just replace the elements offscreen with a single, say <div> element with calculated height
Now, you have heights for all the elements stored in your Data structure, query all the elements that lie before the visible viewport.
Create a <div> with css height set (in pixels) to the sum of the element heights
Mark it with a class name so that you know its a filler div
Remove all the elements from the dom that this div covers
insert this newly created div instead
Repeat for elements that lie after the visible viewport.
Look for scroll and resize events. On each scroll, you will need to go back to your data structure, remove the filler divs, create elements that were previously removed from screen, and accordingly add new filler divs.
:) It's a long, complex method, but for large documents it increased our performance by a large margin.
tl;dr
I'm not sure I explained it properly, but the gist of this method is:
Know the vertical dimensions of your elements
Know the scrolled view port
Represent all off-screen elements with a single div (height equal to the sum of all element heights it covers for)
You will need two divs in total at any given time, one for elements above the visible viewport, one for elements below.
Keep track of the view port by listening for scroll and resize events. Recreate the divs and visible elements accordingly
No experience myself with this, but there are some great tips here: http://engineering.linkedin.com/linkedin-ipad-5-techniques-smooth-infinite-scrolling-html5
I had a look at Facebook and they don't seem to do anything in particular on Firefox. As you scroll down, the DOM elements at the top of the page don't change. Firefox's memory usage climbs to about 500 meg before Facebook doesn't allow you to scroll further.
Twitter appears to be the same as Facebook.
Google Maps is a different story - map tiles out of view are removed from the DOM (although not immediately).
It's 2019. The question is really old, but I think it is still relevant and interesting and maybe something changed as of today, as we all now also tend to use React JS.
I noticed that Facebook's timeline seems to use clusters of content which is hidden with display: none !important as soon as the cluster goes out of view, so all the previously rendered elements of the DOM are kept in the DOM, it's just that those out of view are hidden with display: none !important.
Also, the overall height of the hidden cluster is set to the parent div of the hidden cluster.
Here are some screenshots I've made:
As of 2019, what do you think about this approach? Also, for those who use React, how could it be implemented in React? It would be great to receive your opinions and thoughts regarding this tricky topic.
Thank you for the attention!
While working on a large list of tabular data that needs an easy sorting/filtering system, I discovered the Isotope library, which seems to do exactly what I want, and provides a lot of nice visuals and functionality. I'd like to be able to sort and filter table rows using Isotope, and I've come up with a basic demo that seems to work. However, a few bugs are present:
I'm using the <thead> section for filters and row headers, so I'm applying the Isotope selector to the <tbody>. However, when Isotope is initialized with the tbody as a container, the table cells in each row lose the width assigned by the table formatting. This isn't a huge deal, as I can set column widths manually if I need to, but it is rather annoying in the current context.
The rows are placed outside the table, in the top left of the table's container element. The relative positioning on the tbody element seems to not affect the rows' absolute position style rules (applied automatically by Isotope) as it would with a normal div. Normally, the absolute positioning would be relative to its container element if the container was positioned using either absolute or relative positioning, but this doesn't seem to be the case here.
The table rows are being filtered properly, and the Isotope library is properly applying animations and styling with those exceptions. If at all possible, I'd like to keep the use of tables, as the people maintaining this page will be doing so through a CMS, and don't know enough about HTML or the WYSIWYG editor the CMS uses to consistently produce any HTML structures beyond a fairly basic table. Does anyone have any advice on fixing these two issues? Thanks!
Edit: As an addendum, I've solved the initial problems I was having. Turns out, the tbody element does not accept a position: relative or position: absolute attribute, so the table rows were not being placed properly. Setting the whole table to position: relative solved the main placement issue, though the rows were then moved to the top left of the table. I solved this issue by offsetting the table row top attribute by the height of the thead element in Javascript, since without Javascript the display is normal.
This works beautifully in Firefox, Chrome, Opera, and Safari. However, IE 7, 8, and 9 all have rendering issues--and worse, they're all different rendering issues. IE9 refuses to place the table cells with the correct offset, IE8 doesn't show the rows at all, and IE7 seems to interpret the whole situation to mean "EXPLODE!". At least the main problem I encountered was solved!
I've integrated Wesley's style suggestions to implement Isortope -- a jQuery plugin using Isotope for table sorting.
It addresses things like the column width issue by automatically converting the table's generated column widths into inline styles. That way, the final table displays like the initial one.
Simple demo here.
Download here.
I have a table that has a fixed header and a scrollable body. I want to know the scroll position in the table so that I can reference it on postback and set it to where the user was before postback. I would prefer JQuery to do this, but Javascript is fine too. Im not sure how much code to post here because Im not sure if the problem is that I just dont know the code to do this, or the code I have (css) is interfering with the solutions I have tried.
Any ideas where to start? Is there a method that does this? Ive tried putting this (table style="overflow:auto; height:150" onclick="alert(this.scrollTop)") in the table but it always returns 0.
Ive also tried various JQuery calls as well. They all return 0.
As far as I know (and I am dealing with this kind of stuff everyday), native tables can't handle scrollbars as your describing. I think that probably, your table actually contains a div or other container, which is actually scrolling the table cells. Something like this:
http://jsfiddle.net/mBDjx/46/
I recomend you to inspect your code using the browser developer tools (usually F12) and check if it is only a table, or another element the one which is generating the scroll.
If you realize that is is a div, just check the .scrollTop attribute of the div instead of doing it on the table :-)
Hope it works!
It is the tbody that is scrolling and that is what you need to test. this.scrollTop is referring to the table , and the top of the table is not changing position.
I went through many posts and couldn't find a solution. (I came across with a similar problem in this post, but I can't really related to my exact situation).
Issue: I have to display a large data table (with more than 30 columns) on a screen. My challenge is - the client doesn't like Horizontal scroll bar of any mean.
I am thinking of splitting a table into pieces and using a simple sliders like Jquery: "serialScroll" or "ContentSlider". However, here is another challenge: for 508 compliance, my table needs to be a single table instead of splitting multiple table in different slides.
I am visioning I need a "view finder" div on top of "large table" with control to shift table the size of div Left and Right, http://img202.imageshack.us/i/tableviewfinderidea.jpg/.
My question is:
Is there a JS or Jquery solution out there doing this? (I seriously searched two weeks without any luck.)
Is there any other recommendation?
using a container div styled with 'overflow:hidden' allows you to do the masking as shown in your graphic. then it's easy to move the masked content by setting it to 'position:absolute' and tweaking the 'left' value.
i put a short example of this online at http://jsfiddle.net/BDZPj/
only thing is, you have to know the height of the content being scrolled, as you have to set a height for the mask too. you could read the height from the table on document.ready though, and apply it to the container initially.
anyway, like 'Pointy' says in the comment above, using a standard scrollbar is surely the best way to do it - sometimes the client has to move, too.
I would need to build a html table that has a horizontally scrollable column. The scroll should be placed in the column's header.
My first question is: do you know any jQuery plug-in that is able to do this?
My second question: is this possible using a single table? I've heard that in order to do this you need to use multiple synchronized tables that look like a single one from the user's perspective.
Any idea/advice would be welcomed.
I've only seen something like this using jqGrid, but that was two tables (the master table has a second scrollable table within it). I'd like to know a plugin for this as well...
I would do as you suggested and use 2 containers. They'd both be set to overflow:scroll and have a set width, but the top one would simply contain a div that you can set to be the same width as your table. You can then bind to the "scroll" event in jquery, and set the scroll position of the divs to match each other in that event. Honestly I haven't tried this so I don't know how reliably that event fires, but in theory it should work.
Alternatively, you could do without the standard browser scrollbar and write your own scrollbar that uses javascript to set the position of your table in the overflow:scroll div. If you want draggable behavior (not just left/right arrows), it could be somewhat difficult, but wouldn't be impossible.