spring

Barebones spring animation, based heavily on Rachel Smith's post, with some inspiration from Wobble and boing.js. This package uses ES6+ syntax, including class properties, you might want to run it through Babel first depending on your target browsers.

1. npm install @huth/spring
2. Animate:

  import Spring from "@huth/spring"
  
  let spring = new Spring({ 
      stiffness: 300,
      damping: 70,
      mass: 10,
      delta: .01
  })

  spring.set(100) 
  spring.current // will now get the current value (in a RAF e.g.)

• spring.set(value, fastForward = false) updates the target value, optionally teleporting it
• spring.current returns the current value, use in your own animation loops etc
• spring.stiffness = 300 updates the stiffness property
• spring.damping = 70 updates the damping property
• spring.mass = 10 updates the mass property
• spring.delta = .01 updates the delta property; if target - current is less than this than the spring is considered to have reach its target and will stop animating -- depending on the size of the values you are animating you might want to scale this up or down
• spring.running returns true if not at rest (do not update this manually)
• spring.velocity returns current velocity (do not update this manually)
• spring.acceleration returns current acceleration (do not update this manually)
• spring.target returns current target value (do not update this manually)
• spring.stop() kills the animation loop
• spring.start() starts the animation loop if it is not already running -- you do not need to call this unless you have already stopped the animation manually