adding xlsx functions. mainly to support type checking

Author: Irene Alvarado

examples/xlsx/prices.csv

@@ -0,0 +1,4 @@
+Name,Amount,Price
+One,500,$0.50
+Two,13,$10
+Thre,-3,"$3,000"

examples/xlsx/prices.xlsx

@@ -0,0 +1,14 @@
+import { xlsx, readXLSX } from '../../xlsx.ts'
+import { writeCSV } from '../../csv.ts'
+
+const inputFilename = './examples/xlsx/prices.xlsx'
+const outputFilename = './examples/xlsx/prices.csv'
+
+// read about what the xlsx library can do here: https://github.com/SheetJS/sheetjs
+
+const workbook = await readXLSX(inputFilename)
+const sheetData = workbook.Sheets[workbook.SheetNames[0]]
+const csvString = await xlsx.utils.sheet_to_csv(sheetData) // can use to_json, to_txt, to_html, to_formulae
+
+// Write to csv
+writeCSV(outputFilename, csvString)

examples/xlsx/xlsx-example.ts

@@ -1,3 +1,4 @@
 export * from './json.ts'
 export * from './csv.ts'
-export * from './image.ts'
+export * from './image.ts'
+export * from './xlsx.ts'

mod.ts

@@ -0,0 +1,14 @@
+import xlsxlib from 'https://jspm.dev/xlsx'
+import * as XLSX from 'https://cdn.deno.land/sheetjs/versions/v0.16.8/raw/types/index.d.ts';
+const xlsx = xlsxlib as typeof XLSX;
+
+// read more about the library here: https://github.com/SheetJS/sheetjs
+
+export { xlsx } // export the right types for this lib
+
+// returns a Workbook
+export async function readXLSX(path: string) {
+    const rawText = await Deno.readFile(path)
+    const workbook = await xlsx.read(rawText, { type: 'buffer' })
+    return workbook
+}