# lax.js Simple & lightweight (<4kb gzipped) vanilla JavaScript library to create smooth & beautiful animations when you scroll. ![Lax 2.0 Gif](https://i.imgur.com/XNvvAOv.gif) [>> DEMO <<](https://alexfox.dev/lax.js/) --- ## What's new with Lax.js 2.0 Lax.js 2.0 has been completely re-written with a focus on modularity and flexibility giving you more tools to create awesome animations. - New javascript animation syntax, allowing for more advanced effect combos - Use any value to drive animations, for example mouse position, time of day .. and of course scroll! - Animations can be given inertia when scrolling - Create custom CSS bindings - Animation easings - And much more.. ## Examples - [Scroll effect](https://alexfox.dev/lax.js/examples/scroll) - [Horizontal snap scroll](https://alexfox.dev/lax.js/examples/snap-scroll) - [Inertia](https://alexfox.dev/lax.js/examples/inertia) - [Video/Gif playback](https://alexfox.dev/lax.js/examples/sprite) - [Cursor position](https://alexfox.dev/lax.js/examples/cursor) - [Text input](https://alexfox.dev/lax.js/examples/input) - [Update HTML content](https://alexfox.dev/lax.js/examples/on-update) - [Preset Explorer](https://alexfox.dev/lax.js/preset-explorer) # Documentation ### 1. Getting started - [Setup](#setup) - [Using presets](#using-presets) - [Usage with UI frameworks](#dom-behavior-and-usage-with-frameworks) - [Adding drivers](#adding-drivers) - [Adding elements](#adding-elements) ### 2. Going deeper - [Custom animations](#custom-animations) - [Optimising performance](#optimising-performance) ### 3. Glossary - [CSS properties](#css-properties) - [Special values](#special-values) - [Supported easings](#supported-easings) # Getting started ### NPM Setup ```bash # https://www.npmjs.com/package/lax.js npm install lax.js yarn add lax.js ``` ```js import lax from 'lax.js' ``` ### HTML setup ```html ``` ## Setup To implement lax you need to create at least one _driver_, to provide values for animations, as well as the element animation bindings. Below is a simple example: ```html

Hello

``` ## Using presets The easiest way to get started is to use presets via html classes. For example: ```html

``` Multiple presets can be chained together and they can be customised to suit your needs. Use the [preset explorer](https://alexfox.dev/lax.js/preset-explorer) to explore effects and see a simple example [here](https://alexfox.dev/lax.js/html-inline). ## DOM behavior and usage with Frameworks To increase performance, `lax.js` indexes the list of elements to animate when the page loads. If you're using a library like React, Vue or EmberJS, it is likely that you are adding elements after the initial window.onload. Because of this you will need to call `lax.addElements` when you add components to the DOM that you want to animate, and `lax.removeElements` when the component unmounts. Please find a React example [here](https://codesandbox.io/s/laxjs-react-example-nc4h7). Other examples will be available soon for Vue.js and Angular. ## Adding drivers Drivers provide the values that _drive_ your animations. To set up a driver just call `lax.addDriver` with a name and a function which returns a number. This method is called every frame to calculate the animations so keep the method as computationally _light_ as possible. The example below will be the most common use case for lax which returns the scrollY position of the window. ```javascript lax.addDriver( 'scrollY', // Driver name function(laxFrame) { return window.scrollY // Value method }, { } // Options ) ``` ### Driver options #### `inertiaEnabled: boolean = false` If enabled, the driver will calculate the speed at which its value is changing. Used to add inertia to elements using the [inertia element option](#inertia-number). See this in action in the [here](https://alexfox.dev/lax.js/examples/inertia). #### `frameStep: number = 1` By default each driver updates its value every animation frame, around ~60 times per second. You can use the `frameStep` to reduce frequency of the driver value updating. For example a value of `2` would only update ~30 times per second and a value of `60` would only update about once per second. ## Adding elements You can add lax animations to an element using the `addElements` method: ```javascript lax.addElements( '.selector', // Element selector rule { // Animation data scrollY: { opacity: [ [0, 100], [1, 0] ] } }, { style: {} // Element options } ) ``` ### Element options #### `style: StyleObject` Add static CSS to each element, for example: ```css { transform: '200ms scale ease-in-out'; } ``` #### `onUpdate: (driverValues: Object, domElement: DomElement) => void` A method called every frame with the current driverValues and domElement. This could be used to toggle classes on an element or set innerHTML. See it in action [here](https://alexfox.dev/lax.js/examples/on-update). The driver values are formatted as follows: ```js { scrollY: [ // Driver name 100, // Driver value 0 // Driver inertia ] } ``` # Going deeper ## Custom animations Custom animations are defined using an object. ```javascript // Animation data { scrollY: { // Driver name translateX: [ // CSS property ['elInY', 'elOutY'], // Driver value map [0, 'screenWidth'], // Animation value map { inertia: 10 // Options } ], opacity: [ // etc ] } } ``` ### Driver name The name of the driver you want to use as a source of values to map to your animation, for example, the document's scrollY position. Read about adding drivers [here](#adding-drivers). ### CSS property The name of the CSS property you want to animate, for example `opacity` or `rotate`. See a list of supported properties [here](#css-properties). > Some CSS properties, for example `box-shadow`, require a custom function to build the style string. To do this use the [cssFn](#cssfn-value-number--string) element option. ### Value maps The value maps are used to interpolate the driver value and output a value for your CSS property. For example: ```javascript [0, 200, 800] // Driver value map [0, 10, 20] // Animation value map // Result | In | Out | | --- | --- | | 0 | 0 | | 100 | 5 | | 200 | 10 | | 500 | 15 | | 800 | 20 | ``` Within the maps you can use strings for simple formulas as well as use special values. e.g: ```javascript ['elInY', 'elCenterY-200', 'elCenterY', ``` See a list of available values [here](#special-values). You can also use mobile breakpoints within animation maps for more flexibility. ```javascript scrollY: { translateX: [ ['elInY', 'elCenterY', 'elOutY'], { 500: [10, 20, 50], // Screen width < 500 900: [30, 40, 60], // Screen width > 500 and < 900 1400: [30, 40, 60], // Screen width > 900 }, ]; } ``` ### Options #### `modValue: number | undefined` Set this option to modulus the value from the driver, for example if you want to loop the animation value as the driver value continues to increase. #### `frameStep: number = 1` By default each animation updates its value every animation frame, around ~60 times per second. You can use the `frameStep` to reduce frequency of the animation updating. For example a value of `2` would only update ~30 times per second and a value of `60` would only update about once per second. #### `inertia: number` Use to add inertia to your animations. Use in combination with the [inertiaEnabled](#inertiaenabled-boolean--false) driver option. See inertia in action [here](https://alexfox.dev/lax.js/examples/inertia). #### `inertiaMode: "normal" | "absolute"` Use in combination with `inertia`. If set to `absolute` the inertia value will always be a positive number via the `Math.abs` operator. #### `cssUnit: string = ""` Define the unit to be appended to the end of the value, for example For example `px` `deg` #### `cssFn: (value: number, domElement: DomElement) => number | string` Some CSS properties require more complex strings as values. For example, `box-shadow` has multiple values that could be modified by a lax animation. ```javascript // Box-shadow example (val) => { return `${val}px ${val}px ${val}px rgba(0,0,0,0.5)`; }; ``` #### `easing: string` See a list of available values [here](#supported-easings). ## Optimising performance Lax.js has been designed to be performant but there are a few things to bare in mind when creating your websites. - Smaller elements perform better. - Postion `fixed` and `absolute` elements perform best as they do not trigger a layout change when updated. - Off-screen elements do not need to be updated so consider that when creating your animation value maps. - The css properties `blur`, `hue-rotate` and `brightness` are graphically intensive and do not run as smoothly as the other available properties. # Glossary ## CSS properties | name | | ---------- | | opacity | | scaleX | | scaleY | | scale | | skewX | | skewY | | skew | | rotateX | | rotateY | | rotate | | translateX | | translateY | | translateZ | | blur | | hue-rotate | | brightness | ## Special values | key | value | | ------------ | -------------------------------------------------------------------------------- | | screenWidth | current width of the screen | | screenHeight | current height of the screen | | pageWidth | width of the document | | pageHeight | height of the document | | elWidth | width of the element | | elHeight | height of the element | | elInY | window scrollY position when element will appear at the bottom of the screen | | elOutY | window scrollY position when element will disappear at the top of the screen | | elCenterY | window scrollY position when element will be centered vertically on the screen | | elInX | window scrollX position when element will appear at the right of the screen | | elOutX | window scrollX position when element will disappear at the left of the screen | | elCenterX | window scrollX position when element will be centered horizontally on the screen | | index | index of the element when added using `lax.addElements` | ## Supported easings | name | | -------------- | | easeInQuad | | easeOutQuad | | easeInOutQuad | | easeInCubic | | easeOutCubic | | easeInOutCubic | | easeInQuart | | easeOutQuart | | easeInOutQuart | | easeInQuint | | easeOutQuint | | easeInOutQuint | | easeOutBounce | | easeInBounce | | easeOutBack | | easeInBack |

	Stars	Issues	Version	Updated	Created
lax.js			2.0.3	3 years ago	5 years ago
locomotive-scroll	7,383	262	4.1.4	2 years ago	5 years ago
luxy.js	588	21	0.1.0	6 years ago	6 years ago
rellax			1.12.1	4 years ago	8 years ago
scroll-parallax	276	24	3.0.3	5 years ago	9 years ago

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