To create musical patterns and rhythms in the browser, Tone.js offers specialized tools for precise timing and sequence control. At the heart of rhythmic programming is the Transport object, which acts as a global clock, managing tempo, start/stop behavior, and synchronization for all scheduled musical events. You can set the beats per minute (BPM) using Tone.Transport.bpm.value, and all timed events will follow this master tempo.

For building patterns, the Part object is essential. A Part lets you define a sequence of musical or percussive events, each scheduled at specific times relative to the Transport’s timeline. Each step in a Part can trigger one or more sounds, and you can loop the sequence to create repeating drum machine patterns. By combining Transport and Part, you gain fine-grained control over the timing, structure, and playback of rhythmic elements in your web-based music projects. This approach ensures patterns remain tightly synchronized, even as the tempo changes or multiple sequences run in parallel.