Calculate the linear interpolation between two numbers

Blend from a to b by an amount between 0 and 1.

JavaScript Version 1.0.0 · MIT · .md

function lerp({ a, b, amount }) { return (1 - amount) * a + amount * b; }

Input & expected output

{
  "a": 0,
  "b": 100,
  "amount": 0.25
}

25

The edge case

{
  "a": 10,
  "b": 20,
  "amount": 1.5
}

25

Know the limits

• Amounts outside 0–1 extrapolate, as the edge case shows; clamp first when you need to stay in range.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Convert degrees to radians — Multiply by π and divide by 180.
• Check if a rectangle contains another one — Compare corners: a contains b when b’s corners sit inside or on a’s edges.
• Check if a rectangle overlaps another one — Two rectangles overlap when they overlap on both axes.