Method capture

packages/svelte/src/internal/client/reactivity/batch.js:578–592

* Associate a change to a given source with the current * batch, noting its previous and current values * @param {Value} source * @param {any} value * @param {boolean} [is_derived]

(source, value, is_derived = false)

	 * @param {boolean} [is_derived]
	 */
	capture(source, value, is_derived = false) {
		if (source.v !== UNINITIALIZED && !this.previous.has(source)) {
			this.previous.set(source, source.v);
		}

		// Don't save errors in `batch_values`, or they won't be thrown in `runtime.js#get`
		if ((source.f & ERROR_VALUE) === 0) {
			this.current.set(source, [value, is_derived]);
			batch_values?.set(source, value);
		}

		if (!this.is_fork) {
			source.v = value;
		}
	}

	activate() {
		current_batch = this;