439 lines
13 KiB
Plaintext
439 lines
13 KiB
Plaintext
---
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pagination_prev: getting-started/index
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sidebar_position: 2
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---
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# Tutorial
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SheetJS presents a simple JS interface that works with "Array of Arrays" and
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"Array of JS Objects". The API functions are building blocks that should be
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combined with other JS APIs to solve problems.
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The discussion focuses on the problem solving mindset. API details are covered
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in other parts of the documentation.
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The goal of this example is to generate a XLSX workbook of US President names
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and birthdays. [Click here](#live-demo) to jump to the live demo.
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## Acquire Data
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### Raw Data
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[The raw data is available in JSON form](https://theunitedstates.io/congress-legislators/executive.json).
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For convenience, it has been [mirrored here](https://sheetjs.com/data/executive.json)
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Acquiring the data is straightforward with `fetch`:
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```js
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const url = "https://sheetjs.com/data/executive.json";
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const raw_data = await (await fetch(url)).json();
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```
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The raw data is an Array of objects. This is the data for John Adams:
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```js
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{
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"id": { /* (data omitted) */ },
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"name": {
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"first": "John", // <-- first name
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"last": "Adams" // <-- last name
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},
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"bio": {
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"birthday": "1735-10-19", // <-- birthday
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"gender": "M"
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},
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"terms": [
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{ "type": "viceprez", /* (other fields omitted) */ },
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{ "type": "viceprez", /* (other fields omitted) */ },
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{ "type": "prez", /* (other fields omitted) */ }
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]
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}
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```
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### Filtering for Presidents
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The dataset includes Aaron Burr, a Vice President who was never President!
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`Array#filter` creates a new array with the desired rows. A President served
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at least one term with `type` set to `"prez"`. To test if a particular row has
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at least one `"prez"` term, `Array#some` is another native JS function. The
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complete filter would be:
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```js
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const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
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```
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### Reshaping the Array
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For this example, the name will be the first name combined with the last name
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(`row.name.first + " " + row.name.last`) and the birthday will be available at
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`row.bio.birthday`. Using `Array#map`, the dataset can be massaged in one call:
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```js
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const rows = prez.map(row => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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```
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The result is an array of "simple" objects with no nesting:
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```js
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[
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{ name: "George Washington", birthday: "1732-02-22" },
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{ name: "John Adams", birthday: "1735-10-19" },
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// ... one row per President
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]
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```
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## Create a Workbook
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With the cleaned dataset, `XLSX.utils.json_to_sheet` generates a worksheet:
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```js
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const worksheet = XLSX.utils.json_to_sheet(rows);
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```
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`XLSX.utils.book_new` creates a new workbook and `XLSX.utils.book_append_sheet`
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appends a worksheet to the workbook. The new worksheet will be called "Dates":
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```js
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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```
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## Clean up Workbook
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The data is in the workbook and can be exported.
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There are multiple opportunities for improvement: the headers can be renamed and
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the column widths can be adjusted. [SheetJS Pro](https://sheetjs.com/pro) offers
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additional styling options like cell styling and frozen rows.
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<details><summary><b>Changing Header Names</b> (click to show)</summary>
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By default, `json_to_sheet` creates a worksheet with a header row. In this case,
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the headers come from the JS object keys: "name" and "birthday".
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The headers are in cells `A1` and `B1`. `XLSX.utils.sheet_add_aoa` can write
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text values to the existing worksheet starting at cell `A1`:
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```js
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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```
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</details>
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<details><summary><b>Changing Column Widths</b> (click to show)</summary>
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Some of the names are longer than the default column width. Column widths are
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set by setting the `"!cols"` worksheet property.
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The following line sets the width of column A to approximately 10 characters:
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```js
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worksheet["!cols"] = [ { wch: 10 } ]; // set column A width to 10 characters
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```
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One `Array#reduce` call over `rows` can calculate the maximum width:
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```js
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const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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```
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</details>
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## Export a File
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`XLSX.writeFile` creates a spreadsheet file and tries to write it to the system.
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In the browser, it will try to prompt the user to download the file. In NodeJS,
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it will write to the local directory.
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:::note
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`XLSX.writeFileXLSX` only writes XLSX files and is recommended when the export
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will always be in the `.xlsx` format. `writeFileXLSX` is more amenable to tree
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shaking. This example uses `XLSX.writeFile` since `writeFileXLSX` does not
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support other common export formats like `.xls` or `.xlsb` or `.csv`.
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`compression: true` enables ZIP compression for XLSX and other formats.
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:::
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```js
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true });
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```
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## Live Demo
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This demo runs in the web browser! Click "Click to Generate File!" and the
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browser should generate a XLSX file.
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```jsx live
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function Presidents() { return ( <button onClick={async () => {
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/* fetch JSON data and parse */
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const url = "https://sheetjs.com/data/executive.json";
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const raw_data = await (await fetch(url)).json();
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/* filter for the Presidents */
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const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
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/* flatten objects */
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const rows = prez.map(row => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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/* generate worksheet and workbook */
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const worksheet = XLSX.utils.json_to_sheet(rows);
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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/* fix headers */
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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/* calculate column width */
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const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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/* create an XLSX file and try to save to Presidents.xlsx */
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true });
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}}><b>Click to Generate file!</b></button> ); }
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```
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## Run the Demo Locally
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import Tabs from '@theme/Tabs';
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import TabItem from '@theme/TabItem';
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<Tabs>
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<TabItem value="browser" label="Browser">
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Save the following script to `snippet.html` and open the page. The page must be
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hosted (no `file:///` access).
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<https://sheetjs.com/pres.html> is a hosted version of the page.
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```html
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<body>
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<script src="https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js"></script>
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<script>
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(async() => {
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/* fetch JSON data and parse */
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const url = "https://sheetjs.com/data/executive.json";
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const raw_data = await (await fetch(url)).json();
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/* filter for the Presidents */
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const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
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/* flatten objects */
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const rows = prez.map(row => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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/* generate worksheet and workbook */
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const worksheet = XLSX.utils.json_to_sheet(rows);
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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/* fix headers */
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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/* calculate column width */
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const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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/* create an XLSX file and try to save to Presidents.xlsx */
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true }));
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})();
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</script>
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<body>
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```
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</TabItem>
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<TabItem value="nodejs" label="NodeJS">
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Install the dependencies:
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```bash
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npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz
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```
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Save the following script to `snippet.js` and run `node snippet.js`:
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```js title="snippet.js"
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const XLSX = require("xlsx");
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(async() => {
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/* fetch JSON data and parse */
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const url = "https://sheetjs.com/data/executive.json";
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const raw_data = await (await fetch(url)).json();
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/* filter for the Presidents */
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const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
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/* flatten objects */
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const rows = prez.map(row => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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/* generate worksheet and workbook */
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const worksheet = XLSX.utils.json_to_sheet(rows);
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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/* fix headers */
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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/* calculate column width */
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const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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/* create an XLSX file and try to save to Presidents.xlsx */
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true }));
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})();
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```
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Native `fetch` support was added in NodeJS 18. For older versions of NodeJS,
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the script will throw an error `fetch is not defined`. A third-party library
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like `axios` presents a similar API for fetching data:
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<details><summary><b>Example using axios</b> (click to show)</summary>
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Install the dependencies:
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```bash
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npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz
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```
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The differences in the script are highlighted below.
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```js title="snippet.js"
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const XLSX = require("xlsx");
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// highlight-next-line
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const axios = require("axios");
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(async() => {
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/* fetch JSON data and parse */
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const url = "https://sheetjs.com/data/executive.json";
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// highlight-next-line
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const raw_data = (await axios(url, {responseType: "json"})).data;
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/* filter for the Presidents */
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const prez = raw_data.filter(row => row.terms.some(term => term.type === "prez"));
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/* flatten objects */
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const rows = prez.map(row => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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/* generate worksheet and workbook */
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const worksheet = XLSX.utils.json_to_sheet(rows);
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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/* fix headers */
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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/* calculate column width */
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const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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/* create an XLSX file and try to save to Presidents.xlsx */
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true }));
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})();
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```
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</details>
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</TabItem>
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<TabItem value="deno" label="Deno">
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Save the following script to `snippet.ts` and run with
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`deno run --allow-net --allow-write snippet.ts`:
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```js title="snippet.ts"
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// @deno-types="https://cdn.sheetjs.com/xlsx-latest/package/types/index.d.ts"
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import * as XLSX from 'https://cdn.sheetjs.com/xlsx-latest/package/xlsx.mjs';
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/* fetch JSON data and parse */
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const url = "https://sheetjs.com/data/executive.json";
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const raw_data = await (await fetch(url)).json();
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/* filter for the Presidents */
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const prez = raw_data.filter((row: any) => row.terms.some((term: any) => term.type === "prez"));
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/* flatten objects */
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const rows = prez.map((row: any) => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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/* generate worksheet and workbook */
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const worksheet = XLSX.utils.json_to_sheet(rows);
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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/* fix headers */
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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/* calculate column width */
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const max_width = rows.reduce((w: number, r: any) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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/* create an XLSX file and try to save to Presidents.xlsx */
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true }));
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```
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</TabItem>
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<TabItem value="bun" label="Bun">
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Download <https://cdn.sheetjs.com/xlsx-latest/package/xlsx.mjs> to `xlsx.mjs`
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Save the following script to `snippet.js` and run with `bun snippet.js`:
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```js title="snippet.js"
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import * as XLSX from './xlsx.mjs';
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import * as fs from 'fs';
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XLSX.set_fs(fs);
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/* fetch JSON data and parse */
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const url = "https://sheetjs.com/data/executive.json";
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const raw_data = await (await fetch(url)).json();
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/* filter for the Presidents */
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const prez = raw_data.filter((row) => row.terms.some((term) => term.type === "prez"));
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/* flatten objects */
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const rows = prez.map((row) => ({
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name: row.name.first + " " + row.name.last,
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birthday: row.bio.birthday
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}));
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/* generate worksheet and workbook */
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const worksheet = XLSX.utils.json_to_sheet(rows);
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const workbook = XLSX.utils.book_new();
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XLSX.utils.book_append_sheet(workbook, worksheet, "Dates");
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/* fix headers */
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XLSX.utils.sheet_add_aoa(worksheet, [["Name", "Birthday"]], { origin: "A1" });
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/* calculate column width */
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const max_width = rows.reduce((w, r) => Math.max(w, r.name.length), 10);
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worksheet["!cols"] = [ { wch: max_width } ];
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/* create an XLSX file and try to save to Presidents.xlsx */
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XLSX.writeFile(workbook, "Presidents.xlsx", { compression: true }));
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```
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</TabItem>
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</Tabs> |