feat: uuid: add a fallback to the crypto.randomUUID API (#24)

In a secureContext, browser's function to generate uuid will be used. This adds a fallback to use a custom local function in insecure contexts (for instance tests). Fix #22

src/dropzone.js

@@ -740,7 +740,7 @@ export default class Dropzone extends Emitter {
   addFile(file) {
     file.upload = {
       // note: this only works if window.isSecureContext is true, which includes localhost in http
-      uuid: self.crypto.randomUUID(),
+      uuid: window.isSecureContext ? self.crypto.randomUUID() : Dropzone.uuidv4(),
       progress: 0,
       // Setting the total upload size to file.size for the beginning
       // It's actual different than the size to be transmitted.
@@ -1707,6 +1707,17 @@ export default class Dropzone extends Emitter {
       return this.processQueue();
     }
   }
+
+  static uuidv4() {
+    return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(
+      /[xy]/g,
+      function (c) {
+        let r = (Math.random() * 16) | 0,
+          v = c === "x" ? r : (r & 0x3) | 0x8;
+        return v.toString(16);
+      }
+    );
+  }
 }
 Dropzone.initClass();