146 lines
6.3 KiB
JavaScript
146 lines
6.3 KiB
JavaScript
//==========================================================
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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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if (htmx.version && !htmx.version.startsWith("1.")) {
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console.warn("WARNING: You are using an htmx 1 extension with htmx " + htmx.version +
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". It is recommended that you move to the version of this extension found on https://htmx.org/extensions")
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}
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var api = null;
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function log() {
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//console.log(arguments);
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}
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function mergeHead(newContent, defaultMergeStrategy) {
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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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// if the head tag exists...
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if (headTag) {
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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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htmlDoc.innerHTML = headTag;
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var newHeadTag = htmlDoc.querySelector("head");
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var currentHead = document.head;
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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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// determine merge strategy
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var mergeStrategy = api.getAttributeValue(newHeadTag, "hx-head") || defaultMergeStrategy;
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// get the current head
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for (const currentHeadElt of currentHead.children) {
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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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// 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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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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// 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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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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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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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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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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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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