docs: add readme and jsdoc comments

.github/workflows/publish.yml

@@ -0,0 +1,18 @@
+# .github/workflows/publish.yml
+
+name: Publish
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - uses: actions/checkout@v4
+      - run: npx jsr publish

README.md

@@ -1 +1,85 @@
 # pl2xl
+
+A lightweight library for reading and writing Excel files as Polars DataFrames.
+`pl2xl` enables seamless integration between Polars and Excel, allowing you to
+import data from Excel files directly into a Polars DataFrame and export
+DataFrames back to Excel.
+
+## Installation
+
+This library can be imported using the `jsr` import specifier and relies on the
+`nodejs-polars` package.
+
+### Importing the library in Deno
+
+```typescript
+import { readExcel, writeExcel } from "jsr:@jackfiszr/pl2xl@0.0.1";
+import pl from "npm:nodejs-polars";
+```
+
+### Using the library in Node.js
+
+Install the library in your Node project using `npx jsr`:
+
+```bash
+npx jsr add @jackfiszr/pl2xl
+```
+
+Then import and use it as follows:
+
+```typescript
+import { readExcel, writeExcel } from "@jackfiszr/pl2xl";
+import pl from "nodejs-polars";
+
+// Create a sample DataFrame
+const inputDf = pl.DataFrame({
+  "Name": ["Alice", "Bob", "Charlie"],
+  "Age": [25, 30, 35],
+  "City": ["New York", "Los Angeles", "Chicago"],
+});
+
+// Write the DataFrame to an Excel file
+writeExcel(inputDf, "input.xlsx");
+
+// Read the DataFrame back from the Excel file
+const df = readExcel("input.xlsx");
+console.log("Read DataFrame:", df);
+
+// Modify the DataFrame by increasing the "Age" column by 1
+const modifiedDf = df.withColumn(
+  pl.col("Age").add(1).alias("Age"),
+);
+
+console.log("Modified DataFrame:", modifiedDf);
+
+// Write the modified DataFrame to a new Excel file
+writeExcel(modifiedDf, "output.xlsx");
+console.log("Modified DataFrame written to output.xlsx");
+```
+
+## API
+
+### `readExcel(filePath: string): pl.DataFrame`
+
+Reads data from the first sheet of an Excel file and returns it as a Polars
+DataFrame.
+
+- `filePath`: The path to the Excel file to be read.
+
+**Returns**: A `pl.DataFrame` containing the data from the Excel file.
+
+### `writeExcel(df: pl.DataFrame, filePath: string): void`
+
+Writes a Polars DataFrame to an Excel file.
+
+- `df`: The Polars DataFrame to write to the file.
+- `filePath`: The path to save the Excel file.
+
+## Requirements
+
+- Deno (for Deno usage) or Node.js (for Node usage)
+- `nodejs-polars` and `xlsx` packages
+
+## License
+
+MIT License

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@jackfiszr/pl2xl",
-  "version": "0.0.1",
+  "version": "0.0.2",
   "exports": "./mod.ts",
   "tasks": {
     "dev": "deno run --watch main.ts"

mod.ts

@@ -1,13 +1,29 @@
 import pl from "polars";
 import xlsx from "xlsx";
 
+/**
+ * Reads an Excel file and returns its content as a Polars DataFrame.
+ * This function takes the first sheet of the workbook and converts it to JSON
+ * before loading it into a DataFrame.
+ *
+ * @param filePath - The path to the Excel file to be read.
+ * @returns A Polars DataFrame containing the data from the first sheet of the Excel file.
+ */
 function readExcel(filePath: string): pl.DataFrame {
   const workbook = xlsx.readFile(filePath);
   const sheet = workbook.Sheets[workbook.SheetNames[0]];
   const jsonData = xlsx.utils.sheet_to_json(sheet);
   return pl.DataFrame(jsonData);
 }
 
+/**
+ * Writes a Polars DataFrame to an Excel file.
+ * This function converts the DataFrame to JSON records and writes them to the
+ * specified file, with the data stored in a sheet named "Sheet1".
+ *
+ * @param df - The Polars DataFrame to write to an Excel file.
+ * @param filePath - The path to save the Excel file.
+ */
 function writeExcel(df: pl.DataFrame, filePath: string): void {
   const rows = df.toRecords();
   const newWorkbook = xlsx.utils.book_new();