split out library loader

src/public/javascripts/services/library_loader.js

@@ -0,0 +1,64 @@
+const CKEDITOR = {"js": ["libraries/ckeditor/ckeditor.js"]};
+
+const CODE_MIRROR = {
+    js: [
+        "libraries/codemirror/codemirror.js",
+        "libraries/codemirror/addon/mode/loadmode.js",
+        "libraries/codemirror/addon/fold/xml-fold.js",
+        "libraries/codemirror/addon/edit/matchbrackets.js",
+        "libraries/codemirror/addon/edit/matchtags.js",
+        "libraries/codemirror/addon/search/match-highlighter.js",
+        "libraries/codemirror/mode/meta.js",
+        "libraries/codemirror/addon/lint/lint.js",
+        "libraries/codemirror/addon/lint/eslint.js"
+    ],
+    css: [
+        "libraries/codemirror/codemirror.css",
+        "libraries/codemirror/addon/lint/lint.css"
+    ]
+};
+
+const ESLINT = {js: ["libraries/eslint.js"]};
+
+async function requireLibrary(library) {
+    if (library.css) {
+        library.css.map(cssUrl => requireCss(cssUrl));
+    }
+
+    if (library.js) {
+        for (const scriptUrl of library.js) {
+            await requireScript(scriptUrl);
+        }
+    }
+}
+
+const dynamicallyLoadedScripts = [];
+
+async function requireScript(url) {
+    if (!dynamicallyLoadedScripts.includes(url)) {
+        dynamicallyLoadedScripts.push(url);
+
+        return await $.ajax({
+            url: url,
+            dataType: "script",
+            cache: true
+        })
+    }
+}
+
+async function requireCss(url) {
+    const css = Array
+        .from(document.querySelectorAll('link'))
+        .map(scr => scr.href);
+
+    if (!css.includes(url)) {
+        $('head').append($('<link rel="stylesheet" type="text/css" />').attr('href', url));
+    }
+}
+
+export default {
+    requireLibrary,
+    CKEDITOR,
+    CODE_MIRROR,
+    ESLINT
+}