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With promises: function doTheThing() { return doOneThing() .then(doAnother) .then(doSomeMore) .catch(handleErrors) } With async functions: async function doTheThing() { try { const one = await doOneThing(); const another = await doAnother(...

You can use a column's number (where the leftmost column is '1') to indicate which column to base the sort on, instead of describing the column by its name. Pro: If you think it's likely you might change column names later, doing so won't break this code. Con: This will generally reduce readabilit...

Requirements: Protractor requires the following dependencies to be installed prior to installation: Java JDK 1.7 or higher Node.js v4 or higher Installation: Download and install Node.js from this URL: https://nodejs.org/en/ To see if the Node.js installation is successfull, you can go an...

Defining position as fixed we can remove an element from the document flow and set its position relatively to the browser window. One obvious use is when we want something to be visible when we scroll to the bottom of a long page. #stickyDiv { position:fixed; top:10px; left:10px; } ...

HTML <div class="rotate"></div> CSS .rotate { width: 100px; height: 100px; background: teal; transform: rotate(45deg); } This example will rotate the div by 45 degrees clockwise. The center of rotation is in the center of the div, 50% from left and ...

A context manager is any object that implements two magic methods __enter__() and __exit__() (although it can implement other methods as well): class AContextManager(): def __enter__(self): print("Entered") # optionally return an object return "A-ins...

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To raise an exception use Kernel#raise passing the exception class and/or message: raise StandardError # raises a StandardError.new raise StandardError, "An error" # raises a StandardError.new("An error") You can also simply pass an error message. In this case, the message i...

A custom exception is any class that extends Exception or a subclass of Exception. In general, you should always extend StandardError or a descendant. The Exception family are usually for virtual-machine or system errors, rescuing them can prevent a forced interruption from working as expected. # ...

Use the begin/rescue block to catch (rescue) an exception and handle it: begin # an execution that may fail rescue # something to execute in case of failure end A rescue clause is analogous to a catch block in a curly brace language like C# or Java. A bare rescue like this rescues Stand...

You can handle multiple errors in the same rescue declaration: begin # an execution that may fail rescue FirstError, SecondError => e # do something if a FirstError or SecondError occurs end You can also add multiple rescue declarations: begin # an execution that may fail rescue ...

with other sets # Intersection {1, 2, 3, 4, 5}.intersection({3, 4, 5, 6}) # {3, 4, 5} {1, 2, 3, 4, 5} & {3, 4, 5, 6} # {3, 4, 5} # Union {1, 2, 3, 4, 5}.union({3, 4, 5, 6}) # {1, 2, 3, 4, 5, 6} {1, 2, 3, 4, 5} | {3, 4, 5, 6} # {1, 2, 3, 4, 5, 6} # Difference ...

<input type="button" value="Button Text"> Buttons can be used for triggering actions to occur on the page, without submitting the form. You can also use the <button> element if you require a button that can be more easily styled or contain other elements: <butt...

Substitutability is a principle in object-oriented programming introduced by Barbara Liskov in a 1987 conference keynote stating that, if class B is a subclass of class A, then wherever A is expected, B can be used instead: class A {...} class B extends A {...} public void method(A obj) {...} ...

You can set the timezone that will be used by Django in the settings.py file. Examples: TIME_ZONE = 'UTC' # use this, whenever possible TIME_ZONE = 'Europe/Berlin' TIME_ZONE = 'Etc/GMT+1' Here is the list of valid timezones When running in a Windows environment this must be set to the same a...

Deploying an advanced project template to shared hosting is a bit trickier than a basic one because it has two webroots, which shared hosting webservers don't support. We will need to adjust the directory structure so frontend URL will be http://site.local and backend URL will be http://site.local/a...

Go to Install Neo4j which should detect the OS platform via your web browser, download and follow the usual installation instructions for your OS. Neo4j was created with Java, therefore will run on any platform with Java installed, however the Neo4j team has simplified installation by providing eas...

Today Fortran is mainly used for numerical computation. This very simple example illustrates the basic program structure to solve quadratic equations: program quadratic !a comment !should be present in every separate program unit implicit none real :: a, b, c real :: discriminant...

A button can be disabled by Swift myButton.isEnabled = false Objective-C: myButton.enabled = NO; The button will become gray: If you don't want the button appearance to change when disabled set adjustsImageWhenDisabled to false / NO

Swift label.backgroundColor = UIColor.redColor() label.backgroundColor = .redColor() Swift 3 label.backgroundColor = UIColor.red Objective-C label.backgroundColor = [UIColor redColor];