356 lines
9.3 KiB
JavaScript
356 lines
9.3 KiB
JavaScript
/*
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Server Sent Events Extension
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============================
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This extension adds support for Server Sent Events to htmx. See /www/extensions/sse.md for usage instructions.
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*/
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(function() {
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/** @type {import("../htmx").HtmxInternalApi} */
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var api;
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htmx.defineExtension("sse", {
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/**
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* Init saves the provided reference to the internal HTMX API.
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*
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* @param {import("../htmx").HtmxInternalApi} api
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* @returns void
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*/
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init: function(apiRef) {
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// store a reference to the internal API.
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api = apiRef;
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// set a function in the public API for creating new EventSource objects
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if (htmx.createEventSource == undefined) {
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htmx.createEventSource = createEventSource;
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}
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},
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/**
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* onEvent handles all events passed to this extension.
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*
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* @param {string} name
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* @param {Event} evt
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* @returns void
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*/
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onEvent: function(name, evt) {
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switch (name) {
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case "htmx:beforeCleanupElement":
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var internalData = api.getInternalData(evt.target)
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// Try to remove remove an EventSource when elements are removed
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if (internalData.sseEventSource) {
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internalData.sseEventSource.close();
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}
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return;
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// Try to create EventSources when elements are processed
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case "htmx:afterProcessNode":
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ensureEventSourceOnElement(evt.target);
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registerSSE(evt.target);
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}
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}
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});
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///////////////////////////////////////////////
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// HELPER FUNCTIONS
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///////////////////////////////////////////////
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/**
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* createEventSource is the default method for creating new EventSource objects.
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* it is hoisted into htmx.config.createEventSource to be overridden by the user, if needed.
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*
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* @param {string} url
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* @returns EventSource
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*/
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function createEventSource(url) {
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return new EventSource(url, { withCredentials: true });
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}
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function splitOnWhitespace(trigger) {
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return trigger.trim().split(/\s+/);
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}
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function getLegacySSEURL(elt) {
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var legacySSEValue = api.getAttributeValue(elt, "hx-sse");
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if (legacySSEValue) {
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var values = splitOnWhitespace(legacySSEValue);
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for (var i = 0; i < values.length; i++) {
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var value = values[i].split(/:(.+)/);
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if (value[0] === "connect") {
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return value[1];
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}
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}
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}
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}
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function getLegacySSESwaps(elt) {
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var legacySSEValue = api.getAttributeValue(elt, "hx-sse");
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var returnArr = [];
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if (legacySSEValue != null) {
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var values = splitOnWhitespace(legacySSEValue);
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for (var i = 0; i < values.length; i++) {
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var value = values[i].split(/:(.+)/);
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if (value[0] === "swap") {
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returnArr.push(value[1]);
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}
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}
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}
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return returnArr;
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}
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/**
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* registerSSE looks for attributes that can contain sse events, right
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* now hx-trigger and sse-swap and adds listeners based on these attributes too
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* the closest event source
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*
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* @param {HTMLElement} elt
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*/
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function registerSSE(elt) {
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// Find closest existing event source
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var sourceElement = api.getClosestMatch(elt, hasEventSource);
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if (sourceElement == null) {
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// api.triggerErrorEvent(elt, "htmx:noSSESourceError")
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return null; // no eventsource in parentage, orphaned element
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}
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// Set internalData and source
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var internalData = api.getInternalData(sourceElement);
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var source = internalData.sseEventSource;
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// Add message handlers for every `sse-swap` attribute
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queryAttributeOnThisOrChildren(elt, "sse-swap").forEach(function(child) {
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var sseSwapAttr = api.getAttributeValue(child, "sse-swap");
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if (sseSwapAttr) {
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var sseEventNames = sseSwapAttr.split(",");
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} else {
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var sseEventNames = getLegacySSESwaps(child);
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}
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for (var i = 0; i < sseEventNames.length; i++) {
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var sseEventName = sseEventNames[i].trim();
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var listener = function(event) {
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// If the source is missing then close SSE
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if (maybeCloseSSESource(sourceElement)) {
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return;
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}
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// If the body no longer contains the element, remove the listener
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if (!api.bodyContains(child)) {
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source.removeEventListener(sseEventName, listener);
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}
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// swap the response into the DOM and trigger a notification
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swap(child, event.data);
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api.triggerEvent(elt, "htmx:sseMessage", event);
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};
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// Register the new listener
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api.getInternalData(child).sseEventListener = listener;
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source.addEventListener(sseEventName, listener);
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}
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});
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// Add message handlers for every `hx-trigger="sse:*"` attribute
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queryAttributeOnThisOrChildren(elt, "hx-trigger").forEach(function(child) {
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var sseEventName = api.getAttributeValue(child, "hx-trigger");
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if (sseEventName == null) {
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return;
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}
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// Only process hx-triggers for events with the "sse:" prefix
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if (sseEventName.slice(0, 4) != "sse:") {
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return;
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}
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// remove the sse: prefix from here on out
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sseEventName = sseEventName.substr(4);
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var listener = function() {
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if (maybeCloseSSESource(sourceElement)) {
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return
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}
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if (!api.bodyContains(child)) {
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source.removeEventListener(sseEventName, listener);
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}
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}
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});
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}
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/**
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* ensureEventSourceOnElement creates a new EventSource connection on the provided element.
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* If a usable EventSource already exists, then it is returned. If not, then a new EventSource
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* is created and stored in the element's internalData.
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* @param {HTMLElement} elt
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* @param {number} retryCount
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* @returns {EventSource | null}
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*/
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function ensureEventSourceOnElement(elt, retryCount) {
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if (elt == null) {
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return null;
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}
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// handle extension source creation attribute
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queryAttributeOnThisOrChildren(elt, "sse-connect").forEach(function(child) {
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var sseURL = api.getAttributeValue(child, "sse-connect");
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if (sseURL == null) {
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return;
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}
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ensureEventSource(child, sseURL, retryCount);
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});
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// handle legacy sse, remove for HTMX2
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queryAttributeOnThisOrChildren(elt, "hx-sse").forEach(function(child) {
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var sseURL = getLegacySSEURL(child);
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if (sseURL == null) {
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return;
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}
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ensureEventSource(child, sseURL, retryCount);
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});
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}
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function ensureEventSource(elt, url, retryCount) {
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var source = htmx.createEventSource(url);
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source.onerror = function(err) {
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// Log an error event
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api.triggerErrorEvent(elt, "htmx:sseError", { error: err, source: source });
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// If parent no longer exists in the document, then clean up this EventSource
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if (maybeCloseSSESource(elt)) {
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return;
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}
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// Otherwise, try to reconnect the EventSource
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if (source.readyState === EventSource.CLOSED) {
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retryCount = retryCount || 0;
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var timeout = Math.random() * (2 ^ retryCount) * 500;
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window.setTimeout(function() {
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ensureEventSourceOnElement(elt, Math.min(7, retryCount + 1));
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}, timeout);
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}
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};
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source.onopen = function(evt) {
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api.triggerEvent(elt, "htmx:sseOpen", { source: source });
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}
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api.getInternalData(elt).sseEventSource = source;
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}
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/**
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* maybeCloseSSESource confirms that the parent element still exists.
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* If not, then any associated SSE source is closed and the function returns true.
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*
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* @param {HTMLElement} elt
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* @returns boolean
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*/
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function maybeCloseSSESource(elt) {
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if (!api.bodyContains(elt)) {
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var source = api.getInternalData(elt).sseEventSource;
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if (source != undefined) {
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source.close();
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// source = null
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return true;
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}
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}
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return false;
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}
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/**
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* queryAttributeOnThisOrChildren returns all nodes that contain the requested attributeName, INCLUDING THE PROVIDED ROOT ELEMENT.
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*
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* @param {HTMLElement} elt
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* @param {string} attributeName
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*/
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function queryAttributeOnThisOrChildren(elt, attributeName) {
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var result = [];
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// If the parent element also contains the requested attribute, then add it to the results too.
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if (api.hasAttribute(elt, attributeName)) {
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result.push(elt);
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}
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// Search all child nodes that match the requested attribute
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elt.querySelectorAll("[" + attributeName + "], [data-" + attributeName + "]").forEach(function(node) {
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result.push(node);
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});
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return result;
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}
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/**
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* @param {HTMLElement} elt
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* @param {string} content
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*/
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function swap(elt, content) {
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api.withExtensions(elt, function(extension) {
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content = extension.transformResponse(content, null, elt);
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});
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var swapSpec = api.getSwapSpecification(elt);
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var target = api.getTarget(elt);
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var settleInfo = api.makeSettleInfo(elt);
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api.selectAndSwap(swapSpec.swapStyle, target, elt, content, settleInfo);
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settleInfo.elts.forEach(function(elt) {
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if (elt.classList) {
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elt.classList.add(htmx.config.settlingClass);
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}
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api.triggerEvent(elt, 'htmx:beforeSettle');
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});
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// Handle settle tasks (with delay if requested)
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if (swapSpec.settleDelay > 0) {
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setTimeout(doSettle(settleInfo), swapSpec.settleDelay);
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} else {
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doSettle(settleInfo)();
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}
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}
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/**
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* doSettle mirrors much of the functionality in htmx that
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* settles elements after their content has been swapped.
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* TODO: this should be published by htmx, and not duplicated here
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* @param {import("../htmx").HtmxSettleInfo} settleInfo
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* @returns () => void
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*/
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function doSettle(settleInfo) {
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return function() {
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settleInfo.tasks.forEach(function(task) {
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task.call();
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});
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settleInfo.elts.forEach(function(elt) {
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if (elt.classList) {
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elt.classList.remove(htmx.config.settlingClass);
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}
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api.triggerEvent(elt, 'htmx:afterSettle');
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});
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}
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}
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function hasEventSource(node) {
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return api.getInternalData(node).sseEventSource != null;
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}
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})();
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