Open External URL

import { openURL } from 'quasar'

openURL('http://...')

// full syntax:
openURL(
  String url,
  Function rejectFn, // optional; gets called if window cannot be opened
  Object windowFeatures // optional requested features for the new window
)

It will take care of the quirks involved when running under Cordova, Electron or on a browser, including notifying the user he/she has to acknowledge opening popups.

When wrapping with Cordova (or Capacitor), it’s best (but not “a must do”) if InAppBrowser Cordova plugin is also installed, so that openURL can hook into that.

If running on iOS and cordova-plugin-safariviewcontroller is installed, then openURL will first try to hook into it.

The optional windowFeatures parameter should be an Object with keys from window.open() windowFeatures and Boolean values (as described in the example below). Please note that these features will not be taken into account when openURL does not defers to using window.open().

// example of openURL() with windowFeatures:

openURL(
  'http://...',
  null, // in this example we don't care about the rejectFn()

  // this is the windowFeatures Object param:
  {
    noopener: true, // this is set by default for security purposes
                    // but it can be disabled if specified with a Boolean false value
    menubar: true,
    toolbar: true,
    noreferrer: true,
    // .....any other window features
  }
)

Copy to Clipboard

The following is a helper to copy some text to Clipboard. The method returns a Promise.

import { copyToClipboard } from 'quasar'

copyToClipboard('some text')
  .then(() => {
    // success!
  })
  .catch(() => {
    // fail
  })

Export file

The following is a helper to trigger the browser to start downloading a file with the specified content.

/**
 * Forces browser to download file with specified content
 *
 * @param {*} fileName - String
 * @param {*} rawData - String | ArrayBuffer | ArrayBufferView | Blob
 * @param {*} opts - String (mimeType) or Object
 *                   Object form: { mimeType?: String, byteOrderMark?: String | Uint8Array, encoding?: String }
 * @returns Boolean | Error
 */

The opts parameter is optional and can be a String (mimeType) or an Object with the following form:

• mimeType (optional)

  Examples: ‘application/octect-stream’ (default), ‘text/plain’, ‘application/json’, ‘text/plain;charset=UTF-8’, ‘video/mp4’, ‘image/png’, ‘application/pdf’ https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types

• byteOrderMark (optional)

  (BOM) Example: ‘\uFEFF’ https://en.wikipedia.org/wiki/Byte_order_mark

• encoding (optional)

  Performs a TextEncoder.encode() over the rawData; Example: ‘windows-1252’ (ANSI, a subset of ISO-8859-1) https://developer.mozilla.org/en-US/docs/Web/API/TextEncoder

Examples:

import { exportFile } from 'quasar'

const status = exportFile('important.txt', 'some content')

if (status === true) {
  // browser allowed it
}
else {
  // browser denied it
  console.log('Error: ' + status)
}

import { exportFile } from 'quasar'

const status = exportFile('file.csv', 'éà; ça; 12\nà@€; çï; 13', {
  encoding: 'windows-1252',
  mimeType: 'text/csv;charset=windows-1252;'
})

if (status === true) {
  // browser allowed it
}
else {
  // browser denied it
  console.error('Error: ' + status)
}

Debounce Function

If your App uses JavaScript to accomplish taxing tasks, a debounce function is essential to ensuring a given task doesn’t fire so often that it bricks browser performance. Debouncing a function limits the rate at which the function can fire.

Debouncing enforces that a function not be called again until a certain amount of time has passed without it being called. As in “execute this function only if 100 milliseconds have passed without it being called.”

A quick example: you have a resize listener on the window which does some element dimension calculations and (possibly) repositions a few elements. That isn’t a heavy task in itself but being repeatedly fired after numerous resizes will really slow your App down. So why not limit the rate at which the function can fire?

// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds. If `immediate` is passed, trigger the function on the
// leading edge, instead of the trailing.
import { debounce } from 'quasar'

(Debounced Function) debounce(Function fn, Number milliseconds_to_wait, Boolean immediate)

// Example:
window.addEventListener(
  'resize',
  debounce(function() {
    // .... things to do ...
  }, 300 /*ms to wait*/)
)

Or calling as a method in a .vue file:

methods: {
  myMethod () { .... }
},

created () {
  this.myMethod = debounce(this.myMethod, 500)
}

There’s also a frameDebounce available which delays calling your function until next browser frame is scheduled to run (read about requestAnimationFrame).

import { frameDebounce } from 'quasar'

(Debounced Function) frameDebounce(Function fn)

// Example:
window.addEventListener(
  'resize',
  frameDebounce(function() {
    .... things to do ...
  })
)

Throttle Function

Throttling enforces a maximum number of times a function can be called over time. As in “execute this function at most once every X milliseconds.”

import { throttle } from 'quasar'

(Throttled Function) throttle(Function fn, Number limit_in_milliseconds)

// Example:
window.addEventListener(
  'resize',
  throttle(function() {
    .... things to do ...
  }, 300 /* execute at most once every 0.3s */)
)

Or calling as a method in a .vue file:

methods: {
  myMethod () { .... }
},

created () {
  this.myMethod = throttle(this.myMethod, 500)
}

(Deep) Copy Objects

A basic respawn of jQuery.extend(). Takes same parameters:

import { extend } from 'quasar'

let newObject = extend([Boolean deepCopy], targetObj, obj, ...)

Watch out for methods within objects.

Generate UID

Generate unique identifiers:

import { uid } from 'quasar'

let uid = uid()
// Example: 501e7ae1-7e6f-b923-3e84-4e946bff31a8

Handling event on a DOM event handler

It’s cross-browser.

import { event } from 'quasar'

node.addEventListener('click', evt => {
  // left clicked?
  (Boolean) event.leftClick(evt)

  // middle clicked?
  (Boolean) event.middleClick(evt)

  // right clicked?
  (Boolean) event.rightClick(evt)

  // key in number format
  (Number) event.getEventKey(evt)

  // Mouse wheel distance (in pixels)
  (Object {x, y}) event.getMouseWheelDistance(evt)

  // position on viewport
  // works both for mouse and touch events!
  (Object {top, left}) event.position(evt)

  // get target DOM Element on which mouse or touch
  // event has fired upon
  (DOM Element) event.targetElement(evt)

  // call stopPropagation and preventDefault
  event.stopAndPrevent(evt)
})