Fixes a circular reference possibility for empty additive dragndrop (#…

…195)
Tewr · Jul 20, 2023 · b159a32 · b159a32
1 parent 592438d
commit b159a32
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Showing 3 changed files with 13 additions and 7 deletions.
diff --git a/src/Blazor.FileReader/script/DragnDrop.ts b/src/Blazor.FileReader/script/DragnDrop.ts
@@ -150,13 +150,16 @@ function RegisterDropEvents(this: FileReaderComponent, element: HTMLElement, reg
         ev.preventDefault();
 
         if (ev.target instanceof HTMLElement) {
+            const existingFilePromise = this.elementDataTransfers.get(element);
             const filePromise = new Promise<FileList>(async (resolve, reject) => {
                 try {
                     let files = await getFilesAsync(ev.dataTransfer);
                     if (registerOptions.additive) {
-                        const existing = await this.elementDataTransfers.get(element) ?? new FileList();
-                        if (existing.length > 0) {
-                            files = new ConcatFileList(existing, files);
+                        if (existingFilePromise) {
+                            const existing = await existingFilePromise ?? new FileList();
+                            if (existing.length > 0) {
+                                files = new ConcatFileList(existing, files);
+                            }
                         }
                     }
                     resolve(files);

diff --git a/src/Blazor.FileReader/wwwroot/FileReaderComponent.js b/src/Blazor.FileReader/wwwroot/FileReaderComponent.js
@@ -214,14 +214,17 @@
             const dropHandler = (ev) => {
                 ev.preventDefault();
                 if (ev.target instanceof HTMLElement) {
+                    const existingFilePromise = this.elementDataTransfers.get(element);
                     const filePromise = new Promise((resolve, reject) => __awaiter(this, void 0, void 0, function* () {
                         var _a;
                         try {
                             let files = yield getFilesAsync(ev.dataTransfer);
                             if (registerOptions.additive) {
-                                const existing = (_a = yield this.elementDataTransfers.get(element)) !== null && _a !== void 0 ? _a : new FileList();
-                                if (existing.length > 0) {
-                                    files = new ConcatFileList_1.ConcatFileList(existing, files);
+                                if (existingFilePromise) {
+                                    const existing = (_a = yield existingFilePromise) !== null && _a !== void 0 ? _a : new FileList();
+                                    if (existing.length > 0) {
+                                        files = new ConcatFileList_1.ConcatFileList(existing, files);
+                                    }
                                 }
                             }
                             resolve(files);