Add asBlob method

Useful for cases where you need to have a Blob object. Like downloading using browser extension APIs.

lib/__specs__/main.spec.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect } from "bun:test";
 import { mkConfig } from "../config.ts";
-import { generateCsv } from "../generator.ts";
+import { asBlob, generateCsv } from "../generator.ts";
 import { ConfigOptions } from "../types.ts";
 import { asString } from "../helpers.ts";
 
@@ -343,4 +343,24 @@ describe("ExportToCsv", () => {
 
     expect(firstLine).toBe("Test Csv 2\r");
   });
+
+  describe("asBlob", () => {
+    it("should construct a valid blob based on options", async () => {
+      const options: ConfigOptions = {
+        title: "Test Csv 2",
+        showTitle: true,
+        useBom: false,
+        showColumnHeaders: true,
+        columnHeaders: ["name", "age"],
+      };
+
+      const output = generateCsv(options)(mockData);
+      const blob = asBlob(options)(output);
+      const text = await blob.text();
+
+      expect(blob.type).toBe("text/csv;charset=utf8;");
+      expect(text.split("\n")[0]).toBe("Test Csv 2\r");
+      expect(blob.size).toBe(65);
+    });
+  });
 });

lib/generator.ts

@@ -56,6 +56,26 @@ export const generateCsv =
     return output;
   };
 
+/**
+ * Returns the Blob representation of the CsvOutput generated
+ * by `generateCsv`. This is useful if you need to access the
+ * data for downloading in other contexts; like browser extensions.
+ */
+export const asBlob =
+  (config: ConfigOptions) =>
+  (csvOutput: CsvOutput): Blob => {
+    const withDefaults = mkConfig(config);
+    const data = unpack(csvOutput);
+
+    // Create blob from CsvOutput either as text or csv file.
+    const fileType = withDefaults.useTextFile ? "plain" : "csv";
+    const blob = new Blob([data], {
+      type: `text/${fileType};charset=utf8;`,
+    });
+
+    return blob;
+  };
+
 /**
  *
  * **Only supported in browser environment.**
@@ -77,20 +97,17 @@ export const download =
       );
     }
 
-    const withDefaults = mkConfig(config);
-    const data = unpack(csvOutput);
-
     // Create blob from CsvOutput either as text or csv file.
-    const fileType = withDefaults.useTextFile ? "plain" : "csv";
+    const blob = asBlob(config)(csvOutput);
+
+    const withDefaults = mkConfig(config);
     const fileExtension = withDefaults.useTextFile ? "txt" : "csv";
-    let blob = new Blob([data], {
-      type: `text/${fileType};charset=utf8;`,
-    });
+    const fileName = `${withDefaults.filename}.${fileExtension}`;
 
     // Create link element in the browser and set the download
     // attribute to the blob that was created.
-    let link = document.createElement("a");
-    link.download = `${withDefaults.filename}.${fileExtension}`;
+    const link = document.createElement("a");
+    link.download = fileName;
     link.href = URL.createObjectURL(blob);
 
     // Ensure the link isn't visible to the user or cause layout shifts.