Merge pull request #244 from sebgroup/feat/download-file-util

feat: add download file util

Author: eweseong

jest.config.js

@@ -23,7 +23,8 @@ if (specific.length) {
     testMatch.push("**/*.test.(ts|js)");
 }
 
-collectCoverageFrom.push("!src/index.js");
+collectCoverageFrom.push("!src/index.(ts|js)");
+collectCoverageFrom.push("!src/**/index.(ts|js)");
 
 module.exports = {
     setupFilesAfterEnv: ["<rootDir>/setupTests.js"],

setupTests.js

@@ -1 +1,5 @@
 require("jsdom-global/register");
+
+global.URL.createObjectURL = jest.fn();
+
+global.URL.revokeObjectURL = jest.fn();

src/downloadFile/downloadFile.test.ts

@@ -0,0 +1,31 @@
+import { downloadFile, FileType } from "./downloadFile";
+
+describe("Util: downloadFile", () => {
+    const DUMMY_BASE64_FILE_CONTENT: string = "ZHVtbXkgZmlsZQ==";
+
+    it("should download base64 content successfully", () => {
+        downloadFile(DUMMY_BASE64_FILE_CONTENT, "dummy.pdf", FileType.PDF);
+    });
+
+    it("should download binary content successfully", () => {
+        downloadFile(new ArrayBuffer(20), "dummy.pdf", FileType.PDF);
+    });
+
+    for (const fileType in FileType) {
+        it(`should download ${fileType} file successfully`, () => {
+            downloadFile(
+                DUMMY_BASE64_FILE_CONTENT,
+                `dummy.${fileType.toLowerCase()}`,
+                FileType[fileType]
+            );
+        });
+    }
+
+    it(`should download unknown file type successfully`, () => {
+        downloadFile(
+            DUMMY_BASE64_FILE_CONTENT,
+            `dummy.txt`,
+            undefined as unknown as FileType
+        );
+    });
+});

src/downloadFile/downloadFile.ts

@@ -0,0 +1,75 @@
+export type FileContent = string | ArrayBuffer;
+
+export enum FileType {
+    JSON = "json",
+    PDF = "pdf",
+    SpreadSheet = "xlsx",
+    XML = "xml",
+}
+
+export function downloadFile(
+    content: FileContent,
+    fileName: string,
+    type: FileType
+) {
+    const blob: Blob = toBlob(content, type);
+    save(blob, fileName);
+}
+
+function toBlob(content: FileContent, type: FileType): Blob {
+    const byteArray: Array<ArrayBuffer | Uint8Array> =
+        typeof content === "string" ? toByteArray(content) : [content];
+    return new Blob(byteArray, { type: toContentType(type) });
+}
+
+function toByteArray(
+    base64Data: string,
+    sliceSize: number = 512
+): Array<Uint8Array> {
+    const byteCharacters: string = window.atob(base64Data);
+    const byteArrays: Array<Uint8Array> = [];
+
+    for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
+        const slice: string = byteCharacters.slice(offset, offset + sliceSize);
+        const byteNumbers: Array<number> = new Array(slice.length);
+
+        for (let i = 0; i < slice.length; i++) {
+            byteNumbers[i] = slice.charCodeAt(i);
+        }
+
+        byteArrays.push(new Uint8Array(byteNumbers));
+    }
+
+    return byteArrays;
+}
+
+function toContentType(type: FileType): string {
+    switch (type) {
+        case FileType.PDF:
+            return "application/pdf";
+
+        case FileType.SpreadSheet:
+            return "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
+
+        case FileType.JSON:
+            return "application/json";
+
+        case FileType.XML:
+            return "text/xml";
+
+        default:
+            return "text/plain";
+    }
+}
+
+function save(blob: Blob, fileName: string): void {
+    const url: string = window.URL.createObjectURL(blob);
+    const downloadableLink: HTMLAnchorElement = document.createElement("a");
+    downloadableLink.download = fileName;
+    downloadableLink.href = url;
+    downloadableLink.style.display = "none";
+    document.body.appendChild(downloadableLink);
+    downloadableLink.click();
+    downloadableLink.remove();
+    window.URL.revokeObjectURL(url);
+}

src/downloadFile/index.ts

@@ -0,0 +1 @@
+export * from "./downloadFile";

src/index.ts

@@ -5,6 +5,7 @@ export * from "./clearTime";
 export * from "./CookieStorage";
 export * from "./dateDiff";
 export * from "./deepCopy";
+export * from "./downloadFile";
 export * from "./formatDate";
 export * from "./FormValidator";
 export * from "./getBrowserName";