get_interpolator() — svelte Function Reference

Architecture documentation for the get_interpolator() function in tweened.js from the svelte codebase.

Function javascript SharedInternal DOMUtils calls 1

Entity Profile

SharedInternal→ DOMUtils→ get_interpolator() — svelte Function Reference

Dependency Diagram

graph TD
  b8022161_19de_22af_a730_eb7a4a47b4c2["get_interpolator()"]
  99a316ef_52a9_1ecb_3a20_489761af28ad["tweened.js"]
  b8022161_19de_22af_a730_eb7a4a47b4c2 -->|defined in| 99a316ef_52a9_1ecb_3a20_489761af28ad
  2c01da3b_6fe8_7031_6c99_5ae208e44c66["is_date()"]
  b8022161_19de_22af_a730_eb7a4a47b4c2 -->|calls| 2c01da3b_6fe8_7031_6c99_5ae208e44c66
  style b8022161_19de_22af_a730_eb7a4a47b4c2 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/svelte/src/motion/tweened.js lines 20–79

function get_interpolator(a, b) {
	if (a === b || a !== a) return () => a;

	const type = typeof a;
	if (type !== typeof b || Array.isArray(a) !== Array.isArray(b)) {
		throw new Error('Cannot interpolate values of different type');
	}

	if (Array.isArray(a)) {
		const arr = /** @type {Array<any>} */ (b).map((bi, i) => {
			return get_interpolator(/** @type {Array<any>} */ (a)[i], bi);
		});

		// @ts-ignore
		return (t) => arr.map((fn) => fn(t));
	}

	if (type === 'object') {
		if (!a || !b) {
			throw new Error('Object cannot be null');
		}

		if (is_date(a) && is_date(b)) {
			const an = a.getTime();
			const bn = b.getTime();
			const delta = bn - an;

			// @ts-ignore
			return (t) => new Date(an + t * delta);
		}

		const keys = Object.keys(b);

		/** @type {Record<string, (t: number) => T>} */
		const interpolators = {};
		keys.forEach((key) => {
			// @ts-ignore
			interpolators[key] = get_interpolator(a[key], b[key]);
		});

		// @ts-ignore
		return (t) => {
			/** @type {Record<string, any>} */
			const result = {};
			keys.forEach((key) => {
				result[key] = interpolators[key](t);
			});
			return result;
		};
	}

	if (type === 'number') {
		const delta = /** @type {number} */ (b) - /** @type {number} */ (a);
		// @ts-ignore
		return (t) => a + t * delta;
	}

	// for non-numeric values, snap to the final value immediately
	return () => b;
}