Done with the basics
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TomDo1234
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@ -45,175 +45,75 @@ Workers
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:::
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### Reading Data
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### Overview
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In the Lambda handler, the `event.body` attribute is a Base64-encoded string
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representing the HTTP request form data. This body must be parsed.
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Cloudflare Workers exposes a handler in src/index.(js|ts) when you create a worker project using C3 as per above,
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this handler exposes a Request object which can be used to expose the formdata or json of the request to the worker
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#### Processing Form Bodies
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The `busboy` body parser[^2] is battle-tested in NodeJS deployments.
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`busboy` fires a `'file'` event for every file in the form body. The callback
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receives a NodeJS stream that should be collected into a Buffer:
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```js
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/* accumulate the files manually */
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var files = {};
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bb.on('file', function(fieldname, file, filename) {
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/* concatenate the individual data buffers */
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var buffers = [];
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file.on('data', function(data) { buffers.push(data); });
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file.on('end', function() { files[fieldname] = Buffer.concat(buffers); });
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});
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```
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`busboy` fires a `'finish'` event when the body parsing is finished. Callbacks
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can assume every file in the form body has been stored in NodeJS Buffer objects.
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#### Processing NodeJS Buffers
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The SheetJS `read` method[^3] can read the Buffer objects and generate SheetJS
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workbook objects[^4] which can be processed with other API functions.
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For example, a handler can use `sheet_to_csv`[^5] to generate CSV text:
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```js
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/* on the finish event, all of the fields and files are ready */
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bb.on('finish', function() {
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/* grab the first file */
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var f = files["upload"];
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if(!f) callback(new Error("Must submit a file for processing!"));
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/* f[0] is a buffer */
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// highlight-next-line
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var wb = XLSX.read(f[0]);
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/* grab first worksheet and convert to CSV */
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var ws = wb.Sheets[wb.SheetNames[0]];
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callback(null, { statusCode: 200, body: XLSX.utils.sheet_to_csv(ws) });
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});
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```
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<details><summary><b>Complete Code Sample</b> (click to show)</summary>
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This example takes the first uploaded file submitted with the key `upload`,
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parses the file and returns the CSV content of the first worksheet.
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```js
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const XLSX = require('xlsx');
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var Busboy = require('busboy');
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exports.handler = function(event, context, callback) {
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/* set up busboy */
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var ctype = event.headers['Content-Type']||event.headers['content-type'];
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var bb = Busboy({headers:{'content-type':ctype}});
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/* busboy is evented; accumulate the fields and files manually */
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var fields = {}, files = {};
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bb.on('error', function(err) { callback(null, { body: err.message }); });
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bb.on('field', function(fieldname, val) {fields[fieldname] = val });
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// highlight-start
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bb.on('file', function(fieldname, file, filename) {
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/* concatenate the individual data buffers */
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var buffers = [];
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file.on('data', function(data) { buffers.push(data); });
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file.on('end', function() { files[fieldname] = [Buffer.concat(buffers), filename]; });
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});
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// highlight-end
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/* on the finish event, all of the fields and files are ready */
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bb.on('finish', function() {
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/* grab the first file */
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var f = files["upload"];
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if(!f) callback(new Error("Must submit a file for processing!"));
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/* f[0] is a buffer */
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// highlight-next-line
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var wb = XLSX.read(f[0]);
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/* grab first worksheet and convert to CSV */
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var ws = wb.Sheets[wb.SheetNames[0]];
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callback(null, { statusCode: 200, body: XLSX.utils.sheet_to_csv(ws) });
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});
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/* start the processing */
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// highlight-next-line
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bb.end(Buffer.from(event.body, "base64"));
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```ts
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export default {
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async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
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const data = await request.formData()
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// const data = await request.json() if you are receiving a json request
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//...
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},
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};
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```
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</details>
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### Reading Data
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The SheetJS `read` method[^4] can read ArrayBuffer objects and generate SheetJS
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workbook objects[^5] which can be processed with other API functions.
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For example, a handler can use `sheet_to_csv`[^6] to generate CSV text:
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```ts
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import XLSX from "xlsx";
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export default {
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async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
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if (request.method === 'POST') {
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const data = await request.formData()
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// const data = await request.json() if you are doing a json request
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const file = data.get('file') as File;
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const buffer = await file.arrayBuffer();
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const wb = XLSX.read(buffer);
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const ws = wb.Sheets[wb.SheetNames[0]];
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var b64 = XLSX.write(wb, { type: "base64", bookType: "xlsx" });
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return new Response(XLSX.utils.sheet_to_csv(ws))
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}
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return new Response('Hello World!');
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},
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};
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```
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### Writing Data
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For safely transmitting binary data, Base64 strings should be used.
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The SheetJS `write` method[^6] with the option `type: "base64"` will generate
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Base64-encoded strings.
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```js
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/* sample SheetJS workbook object */
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var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
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/* write to XLSX file in Base64 encoding */
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var b64 = XLSX.write(wb, { type: "base64", bookType: "xlsx" });
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```
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The Lambda callback response function accepts options. Setting `isBase64Encoded`
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to `true` will ensure the callback handler decodes the data. To ensure browsers
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will try to download the response, the `Content-Disposition` header must be set:
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```js
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callback(null, {
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statusCode: 200,
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/* Base64-encoded file */
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isBase64Encoded: true,
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body: b64,
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headers: {
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/* Browsers will treat the response as the file SheetJSLambda.xlsx */
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"Content-Disposition": 'attachment; filename="SheetJSLambda.xlsx"'
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}
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});
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```
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<details><summary><b>Complete Code Sample</b> (click to show)</summary>
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This example creates a sample workbook object and sends the file in the response:
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```js
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var XLSX = require('xlsx');
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exports.handler = function(event, context, callback) {
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/* make workbook */
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var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
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/* write to XLSX file in Base64 encoding */
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// highlight-next-line
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var body = XLSX.write(wb, { type: "base64", bookType: "xlsx" });
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/* mark as attached file */
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var headers = { "Content-Disposition": 'attachment; filename="SheetJSLambda.xlsx"'};
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/* Send back data */
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callback(null, {
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statusCode: 200,
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// highlight-next-line
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isBase64Encoded: true,
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body: body,
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headers: headers
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});
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```ts
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import XLSX from "xlsx";
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export default {
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async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
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var wb = XLSX.read("S,h,e,e,t,J,S\n5,4,3,3,7,9,5", {type: "binary"});
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var data = XLSX.write(wb, { type: "buffer", bookType: "xlsx" });
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return new Response(data,{
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status: 200,
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headers: {
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"Content-Disposition": 'attachment; filename="SheetJSCFWorker.xlsx"' //Content disposition will make the browser download the file
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}
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})
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},
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};
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```
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</details>
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### Lambda Demo
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### Cloudflare Workers Demo
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:::note pass
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At the time of writing, the Cloudflare Free Tier included an allowance of 1 million
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free requests per month and 400 thousand GB-seconds of compute resources.
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At the time of writing, the Cloudflare Workers Free Tier included an allowance of 100,000
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free requests per day and 10 milliseconds of CPU time per invocation.
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:::
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0) If you do not have an account, create a new Cloudflare free tier account[^7].
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1) If you do not have an account, create a new account[^7].
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#### Create Project ZIP
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@ -665,10 +565,10 @@ S,h,e,e,t,J,S
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[^1]: See ["Node.js compatibility"](https://developers.cloudflare.com/workers/runtime-apis/nodejs/) in the Cloudflare documentation
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[^2]: See ["Get started guide"](https://developers.cloudflare.com/workers/get-started/guide/#1-create-a-new-worker-project)
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[^3]: [Wrangler documentation](https://developers.cloudflare.com/workers/wrangler/)
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[^4]: See ["Workbook Object" in "SheetJS Data Model"](/docs/csf/book) for more details.
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[^5]: See [`sheet_to_csv` in "CSV and Text"](/docs/api/utilities/csv#delimiter-separated-output)
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[^6]: See [`write` in "Writing Files"](/docs/api/write-options)
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[^7]: Registering for a free account [on the Cloudflare Free Tier](https://Cloudflare.amazon.com/free/) requires a valid phone number and a valid credit card.
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[^4]: See [`read` in "Reading Files"](/docs/api/parse-options)
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[^5]: See ["Workbook Object" in "SheetJS Data Model"](/docs/csf/book) for more details.
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[^6]: See [`sheet_to_csv` in "CSV and Text"](/docs/api/utilities/csv#delimiter-separated-output)
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[^7]: Registering for a free account [on the Cloudflare Free Tier](https://dash.cloudflare.com/sign-up).
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[^8]: The `Cloudflare-sdk` module is distributed [on the public NPM registry](https://npm.im/Cloudflare-sdk)
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[^9]: See ["Managing access keys for IAM users"](https://docs.Cloudflare.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html) in the Cloudflare documentation
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[^10]: See [`read` in "Reading Files"](/docs/api/parse-options)
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