Tutorial: Mobile Shake Detection

"The accelerometer provides values for X, Y, and Z axes. To detect a shake regardless of the phone's orientation, we calculate the total magnitude of the acceleration vector. Formula: Magnitude = √(x² + y² + z²) We use accelerationIncludingGravity. A stationary phone has a magnitude of roughly 9.8 (Earth's gravity). A shake usually produces a spike over 15 or 20."

"We add a "Debounce" timer. Without this, a single physical shake might fire the code 50 times in one second. We force the code to wait (e.g., 1000ms) before detecting a new shake. let lastShake = 0; const MIN_INTERVAL = 1000; // Wait 1 sec between shakes function handleMotion(event) { const acc = event.accelerationIncludingGravity; if (!acc) return; // Calculate Magnitude const total = Math.sqrt(acc.x**2 + acc.y**2 + acc.z**2);"

Measure the vector magnitude from accelerometer X, Y, and Z to detect shake regardless of device orientation using Magnitude = √(x² + y² + z²). Use accelerationIncludingGravity; a stationary phone reads roughly 9.8 and a shake typically spikes above 15–20. On iOS 13+, request motion permission via a user interaction before adding a devicemotion listener. Implement a debounce interval (e.g., 1000 ms) to prevent multiple triggers per physical shake. In the motion handler calculate the total magnitude and compare to a threshold (start at 15). When threshold and debounce conditions pass, trigger the shake action.

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