I'm currently trying to optimize our application that uses KnockoutJS for view binding and rendering. We discovered a huge bottleneck with a growing dataset size in the following scenario:
The dataset (observableArray) is displayed in an html table.
50 rows are displayed at the same time.
Each field in the row-model is an observable as the data is inline editable (input, select, ...)
Per row exist 8 selects that are initialized with the Select2 Widget (http://ivaynberg.github.io/select2) and a jQuery datepicker.
I already implemented these KnockoutJS performance tips, which I found on different sites:
The observable array is published with the full dataset (call of the observable) and not with multiple push() calls.
I'm using the template-binding in conjunction with the foreach option, as advised on multiple sites, and not both split up as separate binds.
Datepicker and Select2 are implemented as custom knockout bindingHandlers.
ko.applyBindings is invoked directly with the table-element as second parameter, so that not the whole DOM is bound by knockout.
But the main bottleneck in my opinion seems to be the initialization of the additional widgets. I measured the creation of a Select2 widget, which takes ~15ms. Of course that cummulates quickly with 50 rows and 8 columns. So, a single call on the observable array to load the full dataset takes up to 10 seconds! During this time, the Browser is under heavy load and becomes unresponsive, which is a no-go usability wise.
This leads up to my questions:
Has someone experienced a similar scenario and how was it handled?
Is there a better way to initialize third-party widgets with knockout?
Are there alternative ways (using KnockoutJS) to solve this problem?
Has someone experienced a similar scenario and how was it handled?
I have an interactive table on my page, which I display using the HandsOnTable plugin. The table has about 15 columns and I need to display up to 250 rows.
I bind it to an observableArray, and, at first, the observableArray contained only observables.
I was not satisfied with the speed of it in old versions of IE I am required to maintain (IE8/9, worked ok with IE11/recent Chrome), and made the decision to remove all observables inside the observableArray.
It is not really in the spirit of knockout and I am not so proud of this solution, but it does work much faster.
Handsontable lets you handle some events, in which I update the observableArray just like a regular array and then run the valueHasMutated function to notify the changes of the array.
Likewise, my custom binding handler watches changes on the whole observableArray and updates the table as needed.
I think the other difference with your solution is that Handsontable turns into edit mode only when needed, thus the plugins (like datepicker) load only then.
Is there a better way to initialize third-party widgets with knockout?
Maybe you can enter edit mode only when the line/cell is selected. You could then use an if binding to init and display your widgets only then.
Related
We have a large number of angularJS 1.5 directives (around 100) that we use throughout our applications. We also use slickgrid almost everywhere to display mass amounts of data. A project has recently come up where it would be ideal to be able to use our directives within slickgrid cells. So I've been trying to write a slickgrid editor to generate our directives when you go to edit one of the cells.
It seems as though angularJS doesn't pick up on the directive (because slickgrid doesnt operate within angular) and doesnt attach the element to its lifecycles. so basically the base element and its settings will appear in the HTML like this:
<div class="slick-cell l2 r2 active selected" title="">
<custom-directive></custom-directive>
</div>
but since angularJS doesn't process the directives there's no visible element in the view and none of the transcluded elements are created.
I've tried using $compile to sort of pre render the elements and then send them to slick grid, but that results in multilink errors which I'm not sure how to resolve.
I've also tried using a JS template with the hope that the template could be rendered and then used in a slickgrid editor later, but I haven't had success with that as of yet. I am still trying to make this approach work since I've seen other examples of using templates with slickgrid, but they aren't using angularJS so my situation doesn't quite fit to theirs.
To summarize I'm looking for suggestions on how I might approach this problem. I know slickgrid isn't technically supposed to be used in this fashion but there has to be a way to make this work. Reusing 100+ pieces of code to extend functionality here would be a very huge win.
I have a list with quite a few elements (each of them is a nested div). Each element has a custom onclick handler.
JS updates the list several times per second, this may result in:
adding or removing some elements
changing text in some elements
changing styles in some elements
changing height of some elements
etc.
Most of the time the update makes small changes to the majority of the elements.
To minimize reflows I should remove the list from DOM, make the changes and append it back. The problem I have with this approach is that when user selects some text, the next update will reset the selection. (And the next update comes within a second) If user clicks a button his click may fail to register if there was an update between mose_down and mouse_up.
I understand when the selection resets on text that have been changed. It makes sense. But with such approach any selection in this list will reset.
Is there any better way to do this? How would you implement such list?
This list is fully generated by JS. If I'm removing it from DOM anyway, is there any benefit to modifying it instead of recreating it from scratch? Creating it anew each time would require less code.
This sounds like 2 way data binding, there are a couple of good custom solutions to data-binding answers on here: Handy stack link. Alternatively backbone.js and knockout.js have good techniques amongst quite a few other frameworks (angular ect).
Additionally, if you want to have a pop at it yourself (which I highly recommend to get a better understanding) you could use the proposed 'Object Observe' function. There's some handy documentation with some examples on how this works over at Mozilla. as well as The trusty HTML5 Rocks, which is a nice simple tutorial on using the new Object.Observe functionality, well worth a read.
Hope this helps!
I am porting quite a huge piece of software to an ExtJS Grid. Lots of data (and I mean lots of data) is loaded on-demand into spans that are placed inside grid's cells.
Imagine grid cells having <span id="foo_bar'></span> as content, and special ajax handlers are polling the backend for updated information and once available the spans are filled with it.
Now, in case I collapse some part of the grid and then re-exand them again I loose all automatically filled cell content, and am left with empty spans (which I started from in the first place).
I know the correct way is to setup a store and push all data into the store. But as I've mentioned above: I am porting quite a huge piece of legacy software to ExtJS, and I do not really have much choice here.
Is there a way to automagically push grid cell values to the store?
Update:
A grid is loaded with, suppose, 2000 cells (this can vary tremendously). Every cell contains various grades of HTML, mostly this is , but this can be pretty much anything (including several spans or divs in one cell). In the background there is a comet process pushing new data to the HTML page almost in real time. This data is populated to the corresponding SPANS and DIVs either based on their IDs or class or both.
What I want to achieve is that either:
a) the model for the grid is atomagically updated with the new html content of the cells (how can I achieve this)?
b) when collapsing/expanding tree's nodes the model data is NOT reloaded afresh.
Is either a or b possible? if so — how?
Just update your store when the 'special ajax handlers' successfully return values. In staid of manually messing with the dom.
so in the success callback do something like -> loadData()
Edit:
Seems like you are working with very bad legacy code :) If adding a simple line of code to the ajax handler is a tremendous effort.. You can however attach dom listeners, but it's very bad practice. Here are some events to listen to
Edit:
Here is an example of the use of how you could listen to dom events, it's rather a pure js solution but, meh.. it works..
which one is best table sorter choice i wanted to do
Default filter
Sorting
Pagination
Filter
Which one is the best choice for the table filtering that do above all things?? and Most Important Not Jquery one...!!
This is what I am using : Table_Sort
May I suggest the dojo DataGrid.
The DataGrid (and all related classes/widgets) are separated from the actual data so you can put a filter on the data source in any way you would want. There is a big choice of data stores like a REST store or a simple CSV store.
Sorting can be done in the grid itself, delegated to the store or delegated to the server. Depending on what your need it is it might be wise to sort your set on the server to keep performance high in the browsers.
The page does do paging but not in the conventional way that you can flick through the pages. There might be a plug-in component on the grid to make that possible though but I don't know. The current implementation just renders the pages that are visible and when you scroll it will render additional pages.
For more info and examples:
http://docs.dojocampus.org/dojox/grid/index?action=show&redirect=dojox/grid
In my experience with dojo grid I think you will be best off using the dojox.grid.Enhanced grid. It is a bit faster then the DataGrid and new plug-ins and features are constantly added. And with a bit of reading and hanging out in #dojo it is quite possible to write your own plug-in.
I have 3 sets of tabular data I want to display with a JavaScript framework in ASP.NET MVC. I know I can embed a separate grid in a tab, but this seems inefficient especially when large datasets are involved since I imagine 3 separate grids would be created. I haven't found a JavaScript datagrid which emulates what a spreadsheet does with multiple tabs. This example from YUI might come close though:
http://developer.yahoo.com/yui/examples/datatable/dt_dynamicfilter_source.html
I'm a little familiar with jQuery, but would be willing to switch to any framework which makes this easy. I don't really need to edit the data. Any suggestions?
EDIT: I didn't mean this to be about jQuery. Maybe some details about my scenario would help, as suggested in one of the comments. I want to display tabular data from an ordering system containing thousands of records. I'd like 3 tabs:
All orders entered in the system which haven't been paid for yet.
All orders from a specific vendor.
All orders which have been paid for.
Since each category has thousands of rows, I only want to load data if the user starts paging.
I thought having 3 tabs with 3 separate grids (one within each tab) wouldn't be performant. I haven't actually tried though, so I'm probably guilty of prematurely optimizing. I'm looking for a grid with tab support built-in. I don't think there's one for jQuery. Perhaps ExtJS?
Since you tagged this with Ext JS, I'll mention that it's quite simple to render grids into tabs using Ext JS. It also supports deferred load/render, so that only the first tab/grid would load initially, then the others would be loaded on first access. Without knowing your specific requirements it's hard to comment further.
EDIT (based on edited question): Ext grids don't directly support tabbing, but they can be embedded within a TabPanel as I mentioned for the same effect. However, based on your description, it sounds more like a filtering scenario to me. I don't see the point in having the overhead of multiple grids when only one will ever be visible, and each one's purpose is to show a specific view (i.e. filter) of the same data. I would just have a single grid with a toolbar or some other method of providing your toggle between filters, and use Ext's built-in store filtering/querying to create your views on demand. The Ext grid supports paging out of the box (client or server, in your case it would be server for thousands of records). There is also a very popular plugin called LiveGrid that provides for virtual scroll-paging of large data sets.
I'm not necessarily advocating Ext over any other framework -- I just happen to be most familiar with it and I think it could solve your problem quite nicely. I would suggest trying it out for yourself to be sure.
jQuery Grid is kinda what people use a lot. I use it and it's pretty good.
jqGrid Link
I wouldn't draw a grid with three tabs. I'd use a single grid with a tab control and then load data via jQuery as required.
Or maybe have three PartialViews that you can load dynamically when you hit a tab.
You could also use dhtmlx grid.
You could use JS tab object to create tabs.
And use javascript grid framework to create grids and populate data into grids.