feat(#623): add Cory McArthur's handy injectCSS and injectJS function…

…s to utils

Signed-off-by: peterpeterparker <david.dalbusco@outlook.com>

utils/utils/src/index.ts

@@ -1,2 +1,3 @@
 export * from './utils/utils';
 export * from './utils/image-utils';
+export * from './utils/inject-utils';

utils/utils/src/utils/inject-utils.ts

@@ -0,0 +1,51 @@
+export function injectJS(id: string, src: string): Promise<string> {
+  return new Promise<string>((resolve, reject) => {
+    if (!document) {
+      resolve();
+      return;
+    }
+
+    if (document.getElementById(id)) {
+      resolve('JS already loaded.');
+      return;
+    }
+    const script = document.createElement('script');
+
+    script.id = id;
+    script.async = true;
+    script.defer = true;
+    script.src = src;
+
+    script.addEventListener('load', () => resolve('JS loaded.'));
+
+    script.addEventListener('error', () => reject('Error loading script.'));
+    script.addEventListener('abort', () => reject('Script loading aborted.'));
+
+    document.head.appendChild(script);
+  });
+}
+
+export function injectCSS(id: string, src: string): Promise<string> {
+  return new Promise<string>((resolve, reject) => {
+    if (!document) {
+      resolve();
+      return;
+    }
+
+    if (document.getElementById(id)) {
+      resolve('CSS already loaded.');
+      return;
+    }
+
+    const link = document.createElement('link');
+    link.id = id;
+    link.setAttribute('rel', 'stylesheet');
+    link.setAttribute('href', src);
+
+    link.addEventListener('load', () => resolve('CSS loaded.'));
+
+    link.addEventListener('error', () => reject('Error loading css.'));
+    link.addEventListener('abort', () => reject('CSS loading aborted.'));
+    document.head.appendChild(link);
+  });
+}