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How Session Recording Technology Works: DOM Recording vs Video

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Session recordings work in two ways. Some tools record video. They capture pixels. They record exactly what visitors see. Other tools record the DOM. They capture the document structure. They recreate the page as visitors interact with it. Both approaches record behavior. Both show what visitors do. But they work differently. Video recording is like a camera. It captures everything. DOM recording is like a blueprint. It captures structure. Understanding the difference matters. Video feels more natural. You watch like you're sitting behind the visitor. DOM recording is more efficient. It uses less data. It's faster. But it has limitations. JavaScript-heavy sites might not record well with DOM. Video recording just captures pixels. It works everywhere. Each approach has tradeoffs. Video is comprehensive but heavy. DOM is efficient but limited. Many tools use hybrid approaches. They combine both. Understanding recording technology helps you choose tools. It helps you know what to expect. It helps you trust the data.

This article explains how session recording technology works.

How Video Recording Works

Video recording captures pixels on screen. Like a movie camera pointed at a monitor. Every frame gets recorded. Every interaction appears in the video. Visitors see exactly what the recording shows.

Video recording works with any website. Complex JavaScript. Server-side rendering. Single-page apps. Video captures whatever appears on screen. Nothing special needed.

Video recording generates large files. A five-minute session might be fifty megabytes. Storage costs add up. Bandwidth costs add up. Video tools need robust infrastructure.

Video quality varies. Some tools compress heavily. Quality degrades. Some tools preserve quality. File sizes explode. Tradeoffs exist.

How DOM Recording Works

DOM recording captures the page structure. HTML. CSS. JavaScript state. Instead of recording pixels, tools record changes to the page. When a visitor scrolls, the tool notes the scroll. When they click, the tool notes the click.

DOM recording generates small files. A five-minute session might be one megabyte. Storage is cheap. Bandwidth is low. Infrastructure costs are low.

DOM recording is efficient for storage and transmission. But it's limited. If the page uses complex custom JavaScript, DOM recording might miss interactions. If the page renders dynamically, DOM might not capture all changes.

DOM recording recreates the page. It plays back the session like a video but built from page changes. The recreation should match the original but might have slight differences.

Hybrid Recording Approaches

Many tools use hybrid approaches. They record DOM by default for efficiency. When DOM recording is incomplete, they fall back to video. This combines benefits of both.

Hybrid approaches are smart. Most sessions record efficiently with DOM. Complex sessions fall back to video. Users get quality when needed. Costs stay low otherwise.

Privacy Implications of Different Recording Types

Video recording captures everything including sensitive data. A form field shows keystrokes in the video. A payment page shows credit card numbers. Privacy protection requires heavy masking.

DOM recording is more privacy-friendly. The tool records page structure, not pixels. A form field appears as a form field. The value doesn't show unless specifically transmitted. DOM recording needs less masking.

Privacy matters for compliance. GDPR. CCPA. Privacy-respecting tools use DOM recording. Video recording needs careful configuration to be compliant.

Performance Impact of Recording Methods

Video recording has moderate performance impact. The recording script captures frames. Compression happens. Data gets sent. Most visitors don't notice.

DOM recording has minimal impact. The script notes changes. Small amounts of data get sent. Overhead is tiny. Visitors see no performance change.

Testing your specific site matters. Some sites are sensitive to overhead. Others don't notice. Test before deciding on recording method.

Choosing Between Recording Methods

Choose based on needs. Video recording if you need pixel-perfect capture. DOM recording if you need efficiency. Hybrid if you want both.

Consider your site. Simple sites work fine with DOM. Complex sites might need video. Consider your compliance needs. Privacy-heavy industries should prefer DOM.