docs.sheetjs.com/docz/docs/04-getting-started/03-demos/16-desktop.md

129 lines
3.5 KiB
Markdown
Raw Normal View History

2022-08-03 07:42:37 +00:00
---
sidebar_position: 16
title: Desktop Applications
---
Web technologies like JavaScript and HTML have been adapted to the traditional
app space. Typically these frameworks bundle a JavaScript engine as well as a
windowing framework. SheetJS is compatible with many toolkits.
## NW.js
The [Standalone scripts](../../installation/standalone) can be referenced in a
`SCRIPT` tag from the entry point HTML page.
This demo was tested against NW.js 0.66.0.
<details><summary><b>Complete Example</b> (click to show)</summary>
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:
```
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:
```
npx -p nw-builder nwbuild --mode=build .
```
This will generate the standalone app in the `build\sheetjs-nwjs\` folder.
</details>
### 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](../../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 */
fs.writeFile(filename, wbout, function(err) {
if(!err) return alert("Saved to " + filename);
alert("Error: " + (err.message || err));
});
});
input.click();
```