framer-motion/src/animation/utils/is-animatable.ts

An open source and production-ready motion library for React on the web

import { ResolvedValueTarget } from "../../types"
import { complex } from "style-value-types"

/**
 * Check if a value is animatable. Examples:
 *
 * ✅: 100, "100px", "#fff"
 * ❌: "block", "url(2.jpg)"
 * @param value
 *
 * @internal
 */
export const isAnimatable = (key: string, value: ResolvedValueTarget) => {
    // If the list of keys tat might be non-animatable grows, replace with Set
    if (key === "zIndex") return false

    // If it's a number or a keyframes array, we can animate it. We might at some point
    // need to do a deep isAnimatable check of keyframes, or let Popmotion handle this,
    // but for now lets leave it like this for performance reasons
    if (typeof value === "number" || Array.isArray(value)) return true

    if (
        typeof value === "string" && // It's animatable if we have a string
        complex.test(value) && // And it contains numbers and/or colors
        !value.startsWith("url(") // Unless it starts with "url("
    ) {
        return true
    }

    return false
}