Seating plans. How do we render?

The main goal of any ticketing system is to sell the tickets - this is a pretty obvious statement. However, building a JavaScript seating chart that performs well across devices and venue sizes is more complex than it looks. We will take a dive into the history of seating plan rendering to see how the systems progressed, break down the pros and cons of each approach, and evaluate the solutions that Seatmap.pro offers today.

In this article, we will review the approaches to rendering an interactive seating map from a technical standpoint, covering HTML, SVG, Canvas, and WebGL.

About ten years ago, a need to implement new rendering qualities in ticket sales appeared. This happened after offline; traditional ticket offices started going online. As the transition was happening, more challenges were emerging – both visual and UX. For instance, the first representatives of online ticketing systems were not able to reflect individual seats for bigger venues. The user needed to choose the section first, then zoom in on it and only after that the seats appeared. Despite the inconvenience and lack of visual appeal, his approach can still be found out there.

The way seating plans look and function depend on the way developers decide to render. In essence, this is precisely what we are going to discuss. There are three main ways from which one can choose how to render – we will go through them all in detail further. It can also be said that the following paragraphs will take you on an overview excursion of how rendering has been developing.

HTML Tags

Let’s start with taking a couple of steps back in time. Back in the day, when the seating plans were not as elaborate as the ones we are working on now, all the providers were using pure HTML to render. Now, in 2020, it’s amazing to see HTML still being around. There is, of course, a reason for this:

• HTML is compatible with all the browsers
• It’s fairly easy to develop if choosing this approach

Besides the apparent pros (and HTML Tags being the first applied method of rendering seating plans), there are quite some cons. When it comes to rendering seating plans, the concept of HTML rendering is now quite outdated, and this is for a reason. The problems lie in several dimensions at once:

• HTML is quite rigid. There is almost no way to create something truly exquisite and versatile when using tags.
• Performance suffers quite a bit from the need to load multiple objects

SVG

Scalable Vector Graphics, better known as SVG, is a vector graphic format based on XML. Points, lines, curved lines and polygons are used to create images. When using SVG, it is possible to create images that do not lose quality when being scaled. SVG is also described as “retained-mode” graphic models, as the events and objects become part of the DOM (Document Object Model) tree.

Compared to the previous versions, seating plans rendered with the use of SVG had significant advantages. Generally speaking, using this method gave more freedom to the developers and came with perks such as:

• SVGs are rendered in XML (Extensible Markup Language) – this provides the much-needed boost in load time and performance.
• SVGs allow creating more elaborate images compared to HTML Tags.

SVGs are great for rendering the plans of smaller venues. However, there might be difficulties when trying to squeeze objects in. The most significant down point of SVG is derived from this fact:

• With more objects appearing on the screen, SVG performance deteriorates. This happens since all the elements are being added into the DOM.

HTML Canvas — The JavaScript Seating Chart Standard

is an HTML element that, unlike SVG and Tags, is used for creating raster graphics with JavaScript. This technology allows drawing instantly, without keeping all the elements in the Document Object Model, making it an example of immediate mode. For developers building a JavaScript seating chart, Canvas is the most practical starting point.

Using Canvas in rendering seating plans came around considerably later, so this method is quite more developed than the previous two. Here are some perks that come with using HTML Canvas for a seating chart:

• Canvas allows operating with tons of objects without overall performance degradation – this is the biggest advantage of it compared to the previous two technologies. A JavaScript seating chart built on Canvas can handle venues with 10,000+ seats while maintaining smooth pan and zoom.
• Canvas is great for creating interactive seating maps that consist of numerous elements and details — seats, rows, sections, labels, and status indicators can all be drawn in a single render pass.
• Choosing this method will undoubtedly allow creating more elaborate plans with hover effects, selection highlights, and real-time availability updates.

When it comes to disadvantages, the main one is the lack of built-in accessibility. Since Canvas draws pixels rather than DOM elements, screen readers cannot traverse individual seats without additional ARIA markup or a fallback accessible view.

WebGL

In case there is a need to use something more elaborate, on the level of cutting-edge technology, you could consider going for WebGL. WebGL is a JavaScript API used for rendering interactive 2D and 3D graphics with any browser compatible and without the use of plugins.

As a more modern and, overall, developed approach, WebGL has advantages such as:

• The speed of operating and rendering hundreds of thousands of objects increases drastically
• Great for decreasing the power consumption for Mobile devices

However, just like with the options we have mentioned before, WebGL also comes with some downsides:

• WebGL is more complicated for development. The process of graphics card rendering might be quite different from what developers are usually familiar with
• WebGL only works with compatible browsers

Choosing the Right Technology for Your JavaScript Seating Chart

After years of building seating plan renderers, the Seatmap.pro team has tested every approach described above in production. Here is our practical guidance for choosing the right rendering technology:

Skip HTML Tags. They are outdated for interactive seating maps. The DOM overhead and limited visual capabilities make them unsuitable for any modern ticketing system.

Use SVG for small venues (under 1,000 seats). SVG works well for theaters, conference rooms, and small arenas. Each seat is a DOM element, which means built-in click handling, CSS styling, and accessibility. You also get SVG export for printing. Seatmap.pro’s editor uses SVG for venue schema creation and export.

Use Canvas for mid-to-large venues (1,000–50,000 seats). This is the sweet spot for most JavaScript seating chart implementations. Canvas handles thousands of interactive objects without performance degradation, supports smooth pan/zoom, and renders at 60fps on modern devices. If you are building a ticketing system for stadiums, concert halls, or multi-section arenas, Canvas is the right choice. Seatmap.pro’s booking renderer uses Canvas with WebGL acceleration for exactly this reason.

Use WebGL for extreme scale (50,000+ seats or 3D). WebGL gives you GPU-accelerated rendering for the largest venues and 3D visualization. The development complexity is significantly higher, but the performance ceiling is unmatched. Seatmap.pro leverages WebGL under the hood to render interactive seating maps with hundreds of thousands of objects while keeping power consumption low on mobile devices.

Try It: Seatmap.pro JavaScript Seating Chart SDK

Rather than building a seating chart renderer from scratch, you can integrate Seatmap.pro’s JavaScript SDK into your ticketing platform. The renderer handles Canvas/WebGL rendering, seat selection, real-time availability, and responsive layout out of the box. See the Playground to test it live, or read the SDK documentation to get started.