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+//==========================================================
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+// head-support.js
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+//
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+// An extension to htmx 1.0 to add head tag merging.
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+//==========================================================
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+(function(){
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+
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+ var api = null;
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+
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+ function log() {
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+ //console.log(arguments);
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+ }
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+
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+ function mergeHead(newContent, defaultMergeStrategy) {
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+
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+ if (newContent && newContent.indexOf('<head') > -1) {
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+ const htmlDoc = document.createElement("html");
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+ // remove svgs to avoid conflicts
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+ var contentWithSvgsRemoved = newContent.replace(/<svg(\s[^>]*>|>)([\s\S]*?)<\/svg>/gim, '');
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+ // extract head tag
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+ var headTag = contentWithSvgsRemoved.match(/(<head(\s[^>]*>|>)([\s\S]*?)<\/head>)/im);
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+
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+ // if the head tag exists...
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+ if (headTag) {
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+
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+ var added = []
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+ var removed = []
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+ var preserved = []
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+ var nodesToAppend = []
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+
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+ htmlDoc.innerHTML = headTag;
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+ var newHeadTag = htmlDoc.querySelector("head");
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+ var currentHead = document.head;
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+
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+ if (newHeadTag == null) {
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+ return;
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+ } else {
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+ // put all new head elements into a Map, by their outerHTML
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+ var srcToNewHeadNodes = new Map();
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+ for (const newHeadChild of newHeadTag.children) {
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+ srcToNewHeadNodes.set(newHeadChild.outerHTML, newHeadChild);
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+ }
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+ }
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+
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+
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+
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+ // determine merge strategy
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+ var mergeStrategy = api.getAttributeValue(newHeadTag, "hx-head") || defaultMergeStrategy;
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+
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+ // get the current head
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+ for (const currentHeadElt of currentHead.children) {
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+
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+ // If the current head element is in the map
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+ var inNewContent = srcToNewHeadNodes.has(currentHeadElt.outerHTML);
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+ var isReAppended = currentHeadElt.getAttribute("hx-head") === "re-eval";
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+ var isPreserved = api.getAttributeValue(currentHeadElt, "hx-preserve") === "true";
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+ if (inNewContent || isPreserved) {
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+ if (isReAppended) {
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+ // remove the current version and let the new version replace it and re-execute
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+ removed.push(currentHeadElt);
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+ } else {
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+ // this element already exists and should not be re-appended, so remove it from
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+ // the new content map, preserving it in the DOM
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+ srcToNewHeadNodes.delete(currentHeadElt.outerHTML);
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+ preserved.push(currentHeadElt);
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+ }
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+ } else {
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+ if (mergeStrategy === "append") {
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+ // we are appending and this existing element is not new content
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+ // so if and only if it is marked for re-append do we do anything
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+ if (isReAppended) {
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+ removed.push(currentHeadElt);
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+ nodesToAppend.push(currentHeadElt);
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+ }
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+ } else {
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+ // if this is a merge, we remove this content since it is not in the new head
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+ if (api.triggerEvent(document.body, "htmx:removingHeadElement", {headElement: currentHeadElt}) !== false) {
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+ removed.push(currentHeadElt);
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+ }
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+ }
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+ }
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+ }
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+
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+ // Push the tremaining new head elements in the Map into the
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+ // nodes to append to the head tag
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+ nodesToAppend.push(...srcToNewHeadNodes.values());
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+ log("to append: ", nodesToAppend);
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+
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+ for (const newNode of nodesToAppend) {
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+ log("adding: ", newNode);
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+ var newElt = document.createRange().createContextualFragment(newNode.outerHTML);
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+ log(newElt);
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+ if (api.triggerEvent(document.body, "htmx:addingHeadElement", {headElement: newElt}) !== false) {
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+ currentHead.appendChild(newElt);
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+ added.push(newElt);
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+ }
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+ }
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+
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+ // remove all removed elements, after we have appended the new elements to avoid
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+ // additional network requests for things like style sheets
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+ for (const removedElement of removed) {
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+ if (api.triggerEvent(document.body, "htmx:removingHeadElement", {headElement: removedElement}) !== false) {
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+ currentHead.removeChild(removedElement);
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+ }
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+ }
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+
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+ api.triggerEvent(document.body, "htmx:afterHeadMerge", {added: added, kept: preserved, removed: removed});
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+ }
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+ }
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+ }
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+
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+ htmx.defineExtension("head-support", {
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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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+
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+ htmx.on('htmx:afterSwap', function(evt){
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+ var serverResponse = evt.detail.xhr.response;
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+ if (api.triggerEvent(document.body, "htmx:beforeHeadMerge", evt.detail)) {
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+ mergeHead(serverResponse, evt.detail.boosted ? "merge" : "append");
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+ }
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+ })
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+
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+ htmx.on('htmx:historyRestore', function(evt){
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+ if (api.triggerEvent(document.body, "htmx:beforeHeadMerge", evt.detail)) {
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+ if (evt.detail.cacheMiss) {
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+ mergeHead(evt.detail.serverResponse, "merge");
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+ } else {
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+ mergeHead(evt.detail.item.head, "merge");
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+ }
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+ }
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+ })
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+
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+ htmx.on('htmx:historyItemCreated', function(evt){
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+ var historyItem = evt.detail.item;
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+ historyItem.head = document.head.outerHTML;
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+ })
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+ }
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+ });
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+
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+})()
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