motion/dist/targets/js/easing/get-function.es.js

The Motion library for the web

import { cubicBezier } from './cubic-bezier.es.js';
import { steps } from 'popmotion';
import { noopReturn } from '../../../utils/noop.es.js';

const namedEasings = {
    ease: cubicBezier(0.25, 0.1, 0.25, 1.0),
    "ease-in": cubicBezier(0.42, 0.0, 1.0, 1.0),
    "ease-in-out": cubicBezier(0.42, 0.0, 0.58, 1.0),
    "ease-out": cubicBezier(0.0, 0.0, 0.58, 1.0),
};
const functionArgsRegex = /\((.*?)\)/;
function getEasingFunction(definition) {
    // If already an easing function, return
    if (typeof definition === "function")
        return definition;
    // If an easing curve definition, return bezier function
    if (Array.isArray(definition))
        return cubicBezier(...definition);
    // If we have a predefined easing function, return
    if (namedEasings[definition])
        return namedEasings[definition];
    // If this is a steps function, attempt to create easing curve
    if (definition.startsWith("steps")) {
        const args = functionArgsRegex.exec(definition);
        if (args) {
            const argsArray = args[1].split(",");
            return steps(parseFloat(argsArray[0]), argsArray[1].trim());
        }
    }
    return noopReturn;
}

export { getEasingFunction };