Method _initGlobalObserver

src/core/runtime/reactivity.js:344–366

* Set up the single global MutationObserver and delegated input/change * listeners that power attribute, property, and query tracking.

()

     * listeners that power attribute, property, and query tracking.
     */
    _initGlobalObserver() {
        if (typeof document === "undefined") return;

        if (!this._observer) {
            var reactivity = this;
            this._observer = new MutationObserver(function (mutations) {
                reactivity._handleMutations(mutations);
            });
            this._inputHandler = function (e) { reactivity._handleDOMEvent(e); };
            this._changeHandler = function (e) { reactivity._handleDOMEvent(e); };
        }

        // observe() replaces any prior observation on this target
        this._observer.observe(document, {
            attributes: true,
            childList: true,
            subtree: true
        });

        // addEventListener is idempotent for the same listener+capture combo
        document.addEventListener("input", this._inputHandler, true);
        document.addEventListener("change", this._changeHandler, true);
    }

    /**
     * Handle MutationObserver callbacks. Dispatches to attribute and query