docs.sheetjs.com/docz/docs/03-demos/03-desktop/02-nwjs.md

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---
title: NW.js
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pagination_prev: demos/mobile/index
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sidebar_position: 2
sidebar_custom_props:
summary: Embedded Chromium + NodeJS
---
import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';
The [Standalone scripts](/docs/getting-started/installation/standalone) can be
referenced in a `SCRIPT` tag from the entry point HTML page.
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This demo was tested against NW.js 0.66.0 on 2023 January 07.
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The "Complete Example" creates an app that looks like the screenshots below:
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<table><thead><tr>
<th><a href="#complete-example">macOS</a></th>
<th><a href="#complete-example">Linux</a></th>
</tr></thead><tbody><tr><td>
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![macOS screenshot](pathname:///nwjs/nwm.png)
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</td><td>
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![Linux screenshot](pathname:///nwjs/nwl.png)
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</td></tr></tbody></table>
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## Integration Details
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NW.js provides solutions for reading and writing files.
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### Reading data
The standard HTML5 `FileReader` techniques from the browser apply to NW.js!
NW.js handles the OS minutiae for dragging files into app windows. The
[drag and drop snippet](/docs/solutions/input#example-user-submissions) apply
to DIV elements on the page.
Similarly, file input elements automatically map to standard Web APIs.
For example, assuming a file input element on the page:
```html
<input type="file" name="xlfile" id="xlf" />
```
The event handler would process the event as if it were a web event:
```js
async function handleFile(e) {
const file = e.target.files[0];
const data = await file.arrayBuffer();
/* data is an ArrayBuffer */
const workbook = XLSX.read(data);
/* DO SOMETHING WITH workbook HERE */
}
document.getElementById("xlf").addEventListener("change", handleFile, false);
```
### Writing data
File input elements with the attribute `nwsaveas` show UI for saving a file. The
standard trick is to generate a hidden file input DOM element and "click" it.
Since NW.js does not present a `writeFileSync` in the `fs` package, a manual
step is required:
```js
/* pre-build the hidden nwsaveas input element */
var input = document.createElement('input');
input.style.display = 'none';
input.setAttribute('nwsaveas', 'SheetJSNWDemo.xlsx');
input.setAttribute('type', 'file');
document.body.appendChild(input);
/* show a message if the save is canceled */
input.addEventListener('cancel',function(){ alert("Save was canceled!"); });
/* write to a file on the 'change' event */
input.addEventListener('change',function(e){
/* the `value` is the path that the program will write */
var filename = this.value;
/* use XLSX.write with type "buffer" to generate a buffer" */
/* highlight-next-line */
var wbout = XLSX.write(workbook, {type:'buffer', bookType:"xlsx"});
/* highlight-next-line */
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require("fs").writeFile(filename, wbout, function(err) {
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if(!err) return alert("Saved to " + filename);
alert("Error: " + (err.message || err));
});
});
input.click();
```
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## Complete Example
1) Create a `package.json` file that specifies the entry point:
```json title="package.json"
{
"name": "sheetjs-nwjs",
"author": "sheetjs",
"version": "0.0.0",
"main": "index.html",
"dependencies": {
"nw": "~0.66.0",
"xlsx": "https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz"
}
}
```
2) Download [`index.html`](pathname:///nwjs/index.html) into the same folder.
:::caution
Right-click the link and select "Save Link As...". Left-clicking the link will
try to load the page in your browser. The goal is to save the file contents.
:::
3) Run `npm install` to install dependencies
4) To verify the app works, run in the test environment:
```bash
npx nw .
```
The app will show and you should be able to verify reading and writing by using
the file input element to select a spreadsheet and clicking the export button.
5) To build a standalone app, run the builder:
```bash
npx -p nw-builder nwbuild --mode=build .
```
This will generate the standalone app in the `build\sheetjs-nwjs\` folder.