[Export Styles] Add download button to variable export

packages/export-styles/ui-src/App.css

@@ -1,6 +1,6 @@
 #root,
 .appRoot,
-.saltFlexLayout {
+.viewRoot {
   height: 100%;
 }
 

packages/export-styles/ui-src/__tests__/VariableJsonView.spec.tsx

@@ -3,6 +3,10 @@ import userEvents from "@testing-library/user-event";
 import React from "react";
 import { beforeEach, describe, expect, test, vi } from "vitest";
 import { VariableJsonView } from "../views/VariableJsonView";
+import * as utilExports from "../components/utils";
+
+// Mock out download, `URL.createObjectURL` not supported in test env
+vi.spyOn(utilExports, "downloadBlob").mockImplementation(() => {});
 
 describe("VariableJsonView", () => {
   beforeEach(() => {
@@ -161,4 +165,30 @@ describe("VariableJsonView", () => {
     ).toEqual("");
     expect(screen.getByRole("button", { name: "Export" })).toBeDisabled();
   });
+  test("download JSON button is disabled until export text is available", async () => {
+    const downloadJsonButton = screen.getByRole("button", {
+      name: "Download JSON",
+    });
+    expect(downloadJsonButton).toHaveAttribute("aria-disabled", "true");
+
+    const fileName = "filename.json";
+    const expectedText = "text to be filled in";
+    fireEvent(
+      window,
+      new MessageEvent("message", {
+        data: {
+          pluginMessage: {
+            type: "export-variable-to-json-result",
+            body: expectedText,
+            fileName: fileName,
+          },
+        },
+      })
+    );
+    expect(downloadJsonButton).not.toHaveAttribute("aria-disabled", "true");
+
+    await userEvents.click(downloadJsonButton);
+
+    expect(utilExports.downloadBlob).toHaveBeenCalledOnce();
+  });
 });

packages/export-styles/ui-src/components/utils.ts

@@ -0,0 +1,29 @@
+export const downloadDataUri = (dataUri: string, fileName: string) => {
+  const link = document.createElement("a");
+  link.href = dataUri;
+  link.download = fileName;
+  // some browser needs the anchor to be in the doc
+  document.body.append(link);
+  link.click();
+  link.remove();
+  // in case the Blob uses a log of memory
+  setTimeout(() => {
+    URL.revokeObjectURL(link.href);
+  }, 7000);
+};
+
+/**
+ * This is much more efficient than manually converting a Blob or Uint8Array (e.g. `new Blob([uint8Array])`) to string / dataUri.
+ */
+export const downloadBlob = (blob: Blob, fileName: string) => {
+  const link = document.createElement("a");
+  // create a blobURI pointing to our Blob
+  link.href = URL.createObjectURL(blob);
+  link.download = fileName;
+  // some browser needs the anchor to be in the doc
+  document.body.append(link);
+  link.click();
+  link.remove();
+  // in case the Blob uses a lot of memory
+  setTimeout(() => URL.revokeObjectURL(link.href), 7000);
+};

packages/export-styles/ui-src/views/ExportCssView.tsx

@@ -67,7 +67,7 @@ export const ExportCssView = () => {
   }, []);
 
   return (
-    <StackLayout gap={1}>
+    <StackLayout gap={1} className="viewRoot">
       <FormField label="Prefix" labelPlacement="left">
         <Input
           value={prefix}

packages/export-styles/ui-src/views/ExportJsonView.tsx

@@ -55,7 +55,7 @@ export const ExportJsonView = () => {
   }, []);
 
   return (
-    <StackLayout gap={1}>
+    <StackLayout gap={1} className="viewRoot">
       <FormField label="Format" labelPlacement="left">
         <Dropdown
           source={ExportColorAllFormats}

packages/export-styles/ui-src/views/VariableJsonView.tsx

@@ -1,13 +1,13 @@
-import { Button, StackLayout, Text } from "@salt-ds/core";
+import { Button, FlexLayout, StackLayout, Text, Tooltip } from "@salt-ds/core";
+import { DownloadIcon } from "@salt-ds/icons";
 import { Dropdown, FormField } from "@salt-ds/lab";
 import React, { useEffect, useId, useRef, useState } from "react";
 import {
-  ExportColorAllFormats,
-  ExportColorFormat,
   FigmaVariableCollection,
   FigmaVariableMode,
   PostToFigmaMessage,
 } from "../../shared-src";
+import { downloadBlob } from "../components/utils";
 import { FigmaToUIMessageEvent } from "../types";
 
 export const VariableJsonView = () => {
@@ -87,8 +87,14 @@ export const VariableJsonView = () => {
     };
   }, []);
 
+  const onDownload = () => {
+    var blob = new Blob([text], { type: "application/json" });
+    // Use blob instead of plain text downloadDataUri, as Safari wipes out new line
+    downloadBlob(blob, fileName);
+  };
+
   return (
-    <StackLayout gap={1}>
+    <StackLayout gap={1} className="viewRoot">
       <FormField label="Collection">
         <Dropdown
           source={collections}
@@ -137,9 +143,22 @@ export const VariableJsonView = () => {
         spellCheck={false}
         aria-labelledby={exportLabel}
       ></textarea>
-      <Button onClick={onCopy} ref={copyButtonRef}>
-        Copy
-      </Button>
+      <FlexLayout gap={1}>
+        <Button onClick={onCopy} ref={copyButtonRef} style={{ flex: 1 }}>
+          Copy
+        </Button>
+
+        <Tooltip placement="top" content="Download data as JSON">
+          <Button
+            focusableWhenDisabled
+            onClick={onDownload}
+            disabled={!fileName}
+            aria-label="Download JSON"
+          >
+            <DownloadIcon />
+          </Button>
+        </Tooltip>
+      </FlexLayout>
     </StackLayout>
   );
 };