const a = { duration: 50 };
a.duration ??= 10;
a.speed ??= 25;
console.log(a.duration); // Expected output: 50
console.log(a.speed); // Expected output: 25
Replacement for:
a.duration = a.duration ?? 10
Category: JavaScript / nodejs
[nodejs] workspaces
If you have subdirectories or additional applications which have its own package.json file, you can add them via the workspaces setting to your main project.
{
"name": "my-project",
"workspaces": [
"./app/*"
]
}
When running npm install it will now also install the dependencies of all projects in the app folder.
[JavaScript] Clone an object containing a file as ArrayBuffer
Use the build in function structuredClone() to copy all kind of complex JS types.
Official documentation: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm#supported_types
Comparison to other copy techniques like spread or json.stringify: https://www.builder.io/blog/structured-clone
[nodejs] Node Version Manager (NVM)
# Install script: https://github.com/nvm-sh/nvm#install--update-script
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.5/install.sh | bash
# check current used node version
node -v
# list local available node versions
nvm list
# list all released node versions
nvm ls-remote
# install specific node version and switch to it
nvm install v20.5.1
# switch to a specific node version, which is already installed
nvm use v20.5.1
[nodejs] ArrayBuffer to Buffer | Uint8Array to Buffer
https://nodejs.org/api/buffer.html
const buffer1 = Buffer.from(ArrayBuffer)
const buffer2 = Buffer.from(Uint8Array)
[nodejs] Create buffer from stream
Using a promise
const streamToBuffer= async () => {
return new Promise(function (resolve, reject) {
const chunks = []
stream.on('data', chunk => chunks.push(chunk))
stream.on('end', () => resolve(Buffer.concat(chunks)))
stream.on("error", err => reject(err))
})
}
const buffer = await streamToBuffer()
A stream is also iterable (see here), so you can also use for await...of (example)
const chunks = []
for await (const chunk of stream) {
chunks.push(chunk)
}
const buffer = Buffer.concat(chunks)
[JavaScript] Format date object using Intl to dd.MM.yyyy, hh:mm:ss
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl
const now = Intl.DateTimeFormat('de', {
dateStyle: 'medium',
timeStyle: 'medium'
}).format( Date.now() )
console.log( now )
[PDF.js] Set filename when downloading pdf
When using a blob or base64 data to open a file in PDF.js, the viewer is not able to get the correct filename. So when downloading the pdf using the download button inside the viewer, it will always download as document.pdf. To manually set a filename, you can use the setTitleUsingUrl function.
<iframe id="pdf-js-viewer" src="/pdf/web/viewer.html?file=" title="webviewer" frameborder="0" width="100%" height="700" allowfullscreen="" webkitallowfullscreen=""/>
let pdfViewerIFrame = document.getElementById("pdf-js-viewer")
pdfViewerIFrame.contentWindow.PDFViewerApplication.setTitleUsingUrl("myFilename")
More info here: https://github.com/mozilla/pdf.js/issues/10435
[JavaScript] Create date object from date string yyyyMMdd
Using regex, you can simply reorder the parts of your date string to create a compatible ISO 8601 date string which is accepted by the new Date() constructor.
const date_string = "20220101"
const oDate = new Date(date_string.replace(/(\d{4})(\d{2})(\d{2})/, '$1-$2-$3'))
console.log(oDate.toUTCString())
[JavaScript] Convert null to boolean using !!
As null belongs to the JS Falsy Values, you can simply do this:
console.log(null) // null
console.log(!!null) // false
Detailed explanation: https://www.samanthaming.com/tidbits/19-2-ways-to-convert-to-boolean/