@ionic/core/components/watch-options.js

Base components for Ionic

/*!
 * (C) Ionic http://ionicframework.com - MIT License
 */
const watchForOptions = (containerEl, tagName, onChange) => {
    if (typeof MutationObserver === 'undefined') {
        return;
    }
    const mutation = new MutationObserver((mutationList) => {
        onChange(getSelectedOption(mutationList, tagName));
    });
    mutation.observe(containerEl, {
        childList: true,
        subtree: true,
    });
    return mutation;
};
const getSelectedOption = (mutationList, tagName) => {
    let newOption;
    mutationList.forEach((mut) => {
        // eslint-disable-next-line @typescript-eslint/prefer-for-of
        for (let i = 0; i < mut.addedNodes.length; i++) {
            newOption = findCheckedOption(mut.addedNodes[i], tagName) || newOption;
        }
    });
    return newOption;
};
/**
 * The "value" key is only set on some components such as ion-select-option.
 * As a result, we create a default union type of HTMLElement and the "value" key.
 * However, implementers are required to provide the appropriate component type
 * such as HTMLIonSelectOptionElement.
 */
const findCheckedOption = (node, tagName) => {
    /**
     * https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeType
     * The above check ensures "node" is an Element (nodeType 1).
     */
    if (node.nodeType !== 1) {
        return undefined;
    }
    // HTMLElement inherits from Element, so we cast "el" as T.
    const el = node;
    const options = el.tagName === tagName.toUpperCase() ? [el] : Array.from(el.querySelectorAll(tagName));
    return options.find((o) => o.value === el.value);
};

export { watchForOptions as w };