Tutorial by Examples: b

Spawning a process to run an executable

If you are looking to run a file, such as an executable, use child_process.execFile. Instead of spawning a shell like child_process.exec would, it will directly create a new process, which is slightly more efficient than running a command. The function can be used like so: const execFile = require(...

Mutability

Enums can be mutable, this is another way to obtain a singleton behavior: enum class Planet(var population: Int = 0) { EARTH(7 * 100000000), MARS(); override fun toString() = "$name[population=$population]" } println(Planet.MARS) // MARS[population=0] Planet.MARS.p...
Kotlin • Enum

Looping over iterables

You can loop over any iterable by using the standard for-loop: val list = listOf("Hello", "World", "!") for(str in list) { print(str) } Lots of things in Kotlin are iterable, like number ranges: for(i in 0..9) { print(i) } If you need an index while...

Break and continue

Break and continue keywords work like they do in other languages. while(true) { if(condition1) { continue // Will immediately start the next iteration, without executing the rest of the loop body } if(condition2) { break // Will exit the loop completely } } ...

Basic Element Structure

We got the following very basic element my-element saved as src/my-element.html <link rel="import" href="bower_components/polymer/polymer.html"> <dom-module id="my-element"> <template> <style> /* local styles go here */ ...

Example showcasing the basic concepts

The following example is an introduction to: Template compilation using underscore Accessing variables in a template Creating a view Rendering a view Showing a view <html> <head> <script src="https://code.jquery.com/jquery-3.1.0.min.js"></script> ...

Creating a Dialog with Tabbed Titlebar

Occasionally, we may want to display dialogs with more than one pane of content. jQuery UI offers tabs that can be used in tandem with a dialog to make this possible. While it may be more common to have tabs within a dialog's content container, this example will demonstrate how to make a list of t...

Hot and Cold Observables

Observables are broadly categorised as Hot or Cold, depending on their emission behaviour. A Cold Observable is one which starts emitting upon request(subscription), whereas a Hot Observable is one that emits regardless of subscriptions. Cold Observable /* Demonstration of a Cold Observable */ Ob...

Creating basic deadlocked system

A deadlock occurs when two competing actions wait for the other to finish, and thus neither ever does. In java there is one lock associated with each object. To avoid concurrent modification done by multiple threads on single object we can use synchronized keyword, but everything comes at a cost....

Using global external libraries without typings

Although modules are ideal, if the library you are using is referenced by a global variable (like $ or _), because it was loaded by a script tag, you can create an ambient declaration in order to refer to it: declare const _: any;

role="banner"

A region that contains mostly site-oriented content, rather than page-specific content. <div role="banner"> <h1>My Site</h1> <ul> <li><a href="/">Home</a></li> <li><a href="/about">About</...
HTML • ARIA

role="button"

An input that allows for user-triggered actions when clicked or pressed. <button role="button">Add</button>
HTML • ARIA

role="checkbox"

A checkable input that has three possible values: true, false, or mixed. <p> <input type="checkbox" role="checkbox" aria-checked="false"> I agree to the terms </p>
HTML • ARIA

role="combobox"

A presentation of a select; usually similar to a textbox where users can type ahead to select an option, or type to enter arbitrary text as a new item in the list. <input type="text" role="combobox" aria-expanded="false"> Typically, you would use JavaScript to...
HTML • ARIA

role="listbox"

A widget that allows the user to select one or more items from a list of choices. <ul role="listbox"> <li>One</li> <li>Two</li> <li>Three</li> </ul> Typically, you would use JavaScript to build the multiple-selection functionali...
HTML • ARIA

role="menubar"

A presentation of menu that usually remains visible and is usually presented horizontally. <ul role="menubar"> <li role="menuitem">File</li> <li role="menuitem">Edit</li> <li role="menuitem">View</li> <...
HTML • ARIA

role="menuitemcheckbox"

A checkable menuitem that has three possible values: true, false, or mixed. <ul role="menu"> <li role="menuitem">Console</li> <li role="menuitem">Layout</li> <li role="menuitemcheckbox" aria-checked="true"&g...
HTML • ARIA

role="progressbar"

An element that displays the progress status for tasks that take a long time. <progress role="progressbar" value="25" max="100">25%</progress>
HTML • ARIA

role="scrollbar"

A graphical object that controls the scrolling of content within a viewing area, regardless of whether the content is fully displayed within the viewing area. <div id="content1">Lorem ipsum...</div> <div role="scrollbar" aria-controls="content1" ...
HTML • ARIA

role="searchbox"

A type of textbox intended for specifying search criteria. <div role="search"> <input role="searchbox" type="text"> <button role="button">Search</button> </div>
HTML • ARIA

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