Version: 0.66

# Easing

The `Easing` module implements common easing functions. This module is used by Animated.timing() to convey physically believable motion in animations.

You can find a visualization of some common easing functions at http://easings.net/

### Predefined animations​

The `Easing` module provides several predefined animations through the following methods:

### Standard functions​

Three standard easing functions are provided:

The `poly` function can be used to implement quartic, quintic, and other higher power functions.

Additional mathematical functions are provided by the following methods:

The following helpers are used to modify other easing functions.

# Reference

## Methods​

### `step0()`​

``static step0(n)``

A stepping function, returns 1 for any positive value of `n`.

### `step1()`​

``static step1(n)``

A stepping function, returns 1 if `n` is greater than or equal to 1.

### `linear()`​

``static linear(t)``

A linear function, `f(t) = t`. Position correlates to elapsed time one to one.

http://cubic-bezier.com/#0,0,1,1

### `ease()`​

``static ease(t)``

A basic inertial interaction, similar to an object slowly accelerating to speed.

http://cubic-bezier.com/#.42,0,1,1

### `quad()`​

``static quad(t)``

A quadratic function, `f(t) = t * t`. Position equals the square of elapsed time.

### `cubic()`​

``static cubic(t)``

A cubic function, `f(t) = t * t * t`. Position equals the cube of elapsed time.

http://easings.net/#easeInCubic

### `poly()`​

``static poly(n)``

A power function. Position is equal to the Nth power of elapsed time.

### `sin()`​

``static sin(t)``

A sinusoidal function.

http://easings.net/#easeInSine

### `circle()`​

``static circle(t)``

A circular function.

http://easings.net/#easeInCirc

### `exp()`​

``static exp(t)``

An exponential function.

http://easings.net/#easeInExpo

### `elastic()`​

``static elastic(bounciness)``

A basic elastic interaction, similar to a spring oscillating back and forth.

Default bounciness is 1, which overshoots a little bit once. 0 bounciness doesn't overshoot at all, and bounciness of N > 1 will overshoot about N times.

http://easings.net/#easeInElastic

### `back()`​

``static back(s)``

Use with `Animated.parallel()` to create a basic effect where the object animates back slightly as the animation starts.

### `bounce()`​

``static bounce(t)``

Provides a basic bouncing effect.

http://easings.net/#easeInBounce

### `bezier()`​

``static bezier(x1, y1, x2, y2)``

Provides a cubic bezier curve, equivalent to CSS Transitions' `transition-timing-function`.

A useful tool to visualize cubic bezier curves can be found at http://cubic-bezier.com/

### `in()`​

``static in(easing);``

Runs an easing function forwards.

### `out()`​

``static out(easing)``

Runs an easing function backwards.

### `inOut()`​

``static inOut(easing)``

Makes any easing function symmetrical. The easing function will run forwards for half of the duration, then backwards for the rest of the duration.