fix: replaced File constructor with Blob for Edge (#1)

Author: Nerlin

src/file.spec.ts

@@ -1,4 +1,25 @@
-import {COMMON_MIME_TYPES, toFileWithPath} from './file';
+import {clone, COMMON_MIME_TYPES, toFileWithPath} from './file';
+
+class MockFile {
+    public lastModified: number = 0;
+    public name: string = '';
+    public size: number = 0;
+    public type: string = '';
+    public blob: Blob;
+
+    constructor(fileBits: BlobPart[], fileName: string, options: FilePropertyBag) {
+        this.lastModified = options.lastModified || 0;
+        this.name = fileName;
+        this.type = options.type || '';
+        this.blob = new Blob(fileBits);
+        this.size = this.blob.size;
+        throw new Error('Error!');
+    }
+
+    public slice() {
+        return this.blob;
+    }
+}
 
 describe('toFile()', () => {
     it('should be an instance of a File', () => {
@@ -56,6 +77,27 @@ describe('toFile()', () => {
         expect(fwp.lastModified).toEqual(file.lastModified);
     });
 
+    it('clones the File as a blob', () => {
+        const g = global as any;
+        const opts: FilePropertyBag = {
+            type: 'plain/text',
+            lastModified: 1234567
+        };
+        const data = JSON.stringify({ping: true});
+        const file = new File([data], 'test.txt', opts);
+        g.OriginalFile = File;
+        g.File = MockFile;
+        const clonedFile = clone(file);
+        g.File = g.OriginalFile;
+
+        expect(clonedFile).toBeInstanceOf(Blob);
+        expect(clonedFile === file).toBe(false);
+        expect(clonedFile.name).toEqual(file.name);
+        expect(clonedFile.type).toEqual(file.type);
+        expect(clonedFile.size).toEqual(file.size);
+        expect(clonedFile.lastModified).toEqual(file.lastModified);
+    });
+
     it('should behave like a File', done => {
         const data = {ping: true};
         const json = JSON.stringify(data);

src/file.ts

@@ -44,10 +44,16 @@ function withMimeType(file: File) {
     return clone(file);
 }
 
-function clone(file: File, type?: string) {
+export function clone(file: File, fType?: string) {
     const data = file.slice();
-    return new File([data], file.name, {
-        lastModified: file.lastModified,
-        type: type || file.type
-    });
+    const {name, lastModified} = file;
+    const type = fType || file.type;
+
+    try {
+        return new File([data], name, {lastModified, type});
+    } catch (e) {
+        const blob = new Blob([data], {type});
+        Object.assign(blob, {name, lastModified});
+        return blob as File;
+    }
 }