Easing / Timing Functions

Easing controls the rate at which an animation progresses. The default easing of the Web Animation API is linear. It evenly tweens between values. This can look unnaturally smooth because things in nature accelerate and decelerate at start and end. A custom cubic-bezier function or using ease is a good place to start toward creating natural looking animations.

Add easing with any supported CSS timing function to the animation:

const timing = just.animate({
    targets: '#element',
    duration: 650,
    easing: 'ease-in', // or 'easeIn'
    web:  {
        opacity: [0, 1]

Just Animate assumes the easing is ease if one is not provided. This is applied to between all keyframes individually.

Just Animate includes the following timing keywords in addition to cubic-bezier() and steps() from CSS:

Name Timing Function
ease cubic-bezier(.25, .1, .25, 1)
easeIn cubic-bezier(.42, 0, 1, 1)
easeInOut cubic-bezier(.42, 0, .58, 1)
easeOut cubic-bezier(0, 0, .58, 1)
linear cubic-bezier(0, 0, 1, 1)
stepEnd steps(1, end)
stepStart steps(1, start)

For more CSS curves, check out Just Curves or go to cubic-bezier.com to design your own.