The termdelta refers to the difference between two values or states.

The name originates from the Greek letter Δ (delta), which is equivalent to the letterD in the Roman alphabet.Delta refers to the use of the letter Δ as a shorthand fordifference.

The termdelta is commonly used when communicating changes in speed, position, or acceleration of a physical or virtual object. It's also used when describing changes in the volume or frequency of sound waves.

For example, when describing how far an object on the screen moves left-to-right, one might use the termdelta x orΔx.

Likewise, given the new value ofX and its old value, you might compute the delta like this:

let deltaX = newX - oldX;

More commonly, you receive the delta and use it to update a saved previous condition:

let newX = oldX + deltaX;

For example, mouse wheel eventsWheelEvent offer the amount the wheel moved since the last event in itsdeltaX,deltaY, anddeltaZ properties.