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79 lines
3.6 KiB
79 lines
3.6 KiB
4 years ago
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function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); if (enumerableOnly) symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; }); keys.push.apply(keys, symbols); } return keys; }
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function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; if (i % 2) { ownKeys(Object(source), true).forEach(function (key) { _defineProperty(target, key, source[key]); }); } else if (Object.getOwnPropertyDescriptors) { Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); } else { ownKeys(Object(source)).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } } return target; }
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function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
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import { MutationObs, isElement } from './dom';
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import { warnNoMutationObserverSupport } from './warn';
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/**
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* Observe a DOM element changes, falls back to eventListener mode
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* @param {Element} el The DOM element to observe
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* @param {Function} callback callback to be called on change
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* @param {object} [options={childList: true, subtree: true}] observe options
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* @see https://stackoverflow.com/questions/3219758
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*/
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var observeDom = function observeDom(el, callback, options)
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/* istanbul ignore next: difficult to test in JSDOM */
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{
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// Handle cases where we might be passed a Vue instance
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el = el ? el.$el || el : null; // Early exit when we have no element
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/* istanbul ignore next: difficult to test in JSDOM */
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if (!isElement(el)) {
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return null;
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} // Exit and throw a warning when `MutationObserver` isn't available
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if (warnNoMutationObserverSupport('observeDom')) {
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return null;
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} // Define a new observer
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var obs = new MutationObs(function (mutations) {
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var changed = false; // A mutation can contain several change records, so we loop
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// through them to see what has changed
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// We break out of the loop early if any "significant" change
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// has been detected
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for (var i = 0; i < mutations.length && !changed; i++) {
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// The mutation record
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var mutation = mutations[i]; // Mutation type
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var type = mutation.type; // DOM node (could be any DOM node type - HTMLElement, Text, comment, etc.)
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var target = mutation.target; // Detect whether a change happened based on type and target
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if (type === 'characterData' && target.nodeType === Node.TEXT_NODE) {
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// We ignore nodes that are not TEXT (i.e. comments, etc.)
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// as they don't change layout
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changed = true;
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} else if (type === 'attributes') {
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changed = true;
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} else if (type === 'childList' && (mutation.addedNodes.length > 0 || mutation.removedNodes.length > 0)) {
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// This includes HTMLElement and text nodes being
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// added/removed/re-arranged
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changed = true;
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}
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} // We only call the callback if a change that could affect
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// layout/size truly happened
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if (changed) {
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callback();
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}
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}); // Have the observer observe foo for changes in children, etc
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obs.observe(el, _objectSpread({
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childList: true,
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subtree: true
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}, options)); // We return a reference to the observer so that `obs.disconnect()`
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// can be called if necessary
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// To reduce overhead when the root element is hidden
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return obs;
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};
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export default observeDom;
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