I Built a Chrome Extension That Remembers Where You Stopped Reading

Short summary

ReadMark, a Chrome extension that saves and restores your scroll position on any page, solves technical challenges of infinite scroll, SPAs, and layout shifts through document fraction positioning. The author details the full implementation: history interception for client-side routing, debounced storage with beforeunload flush, and image-load stability detection. Free for 10 saves; Pro ($4.99) adds unlimited saves, export, and full-text search.

• •Document fraction position (0.0-1.0) instead of absolute scrollY handles infinite scroll and dynamic content reliably
• •Implementation patterns: history.pushState interception, waitForStability cascade with image waits, debounced storage with beforeunload sync
• •UX insight: deferred restoration banner shown only after user scrolls achieves 70% conversion vs. silent restoration

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