Bézier curves can be used to add beautiful effects to CSS transitions and animations. Typing out the full functional notation (e.g. cubic-bezier(0.550, 0.085, 0.680, 0.530)
) – for developers writing Sass, is unnecessary.
Bourbon – a popular Sass mixin library, comes pre-packaged with all of the timing functions declared as variables. If you’re not using Bourbon, feel free to grab these:
$ease: (
in-quad: cubic-bezier(0.550, 0.085, 0.680, 0.530),
in-cubic: cubic-bezier(0.550, 0.055, 0.675, 0.190),
in-quart: cubic-bezier(0.895, 0.030, 0.685, 0.220),
in-quint: cubic-bezier(0.755, 0.050, 0.855, 0.060),
in-sine: cubic-bezier(0.470, 0.000, 0.745, 0.715),
in-expo: cubic-bezier(0.950, 0.050, 0.795, 0.035),
in-circ: cubic-bezier(0.600, 0.040, 0.980, 0.335),
in-back: cubic-bezier(0.600, -0.280, 0.735, 0.045),
out-quad: cubic-bezier(0.250, 0.460, 0.450, 0.940),
out-cubic: cubic-bezier(0.215, 0.610, 0.355, 1.000),
out-quart: cubic-bezier(0.165, 0.840, 0.440, 1.000),
out-quint: cubic-bezier(0.230, 1.000, 0.320, 1.000),
out-sine: cubic-bezier(0.390, 0.575, 0.565, 1.000),
out-expo: cubic-bezier(0.190, 1.000, 0.220, 1.000),
out-circ: cubic-bezier(0.075, 0.820, 0.165, 1.000),
out-back: cubic-bezier(0.175, 0.885, 0.320, 1.275),
in-out-quad: cubic-bezier(0.455, 0.030, 0.515, 0.955),
in-out-cubic: cubic-bezier(0.645, 0.045, 0.355, 1.000),
in-out-quart: cubic-bezier(0.770, 0.000, 0.175, 1.000),
in-out-quint: cubic-bezier(0.860, 0.000, 0.070, 1.000),
in-out-sine: cubic-bezier(0.445, 0.050, 0.550, 0.950),
in-out-expo: cubic-bezier(1.000, 0.000, 0.000, 1.000),
in-out-circ: cubic-bezier(0.785, 0.135, 0.150, 0.860),
in-out-back: cubic-bezier(0.680, -0.550, 0.265, 1.550)
);
@function ease($key) {
@if map-has-key($ease, $key) {
@return map-get($ease, $key);
}
@warn "Unkown '#{$key}' in $ease.";
@return null;
}
Example usage
.example {
animation: there-and-back 2.5s ease(in-quad) infinite alternate;
}
Demo of all
Thanks to Sean Dempsey (@thatseandempsey).
See the Pen Easing Map Get Function by Sean Dempsey (@seanseansean) on CodePen.