Tutorial by Examples: r

Setting up testing with Gulp, Webpack, Karma and Jasmine

The first thing we need is to tell karma to use Webpack to read our tests, under a configuration we set for the webpack engine. Here, I am using babel because I write my code in ES6, you can change that for other flavors, such as Typescript. Or I use Pug (formerly Jade) templates, you don't have to....

Angular 2 • Testing an Angular 2 App

getActive() - Get active spreadsheet

This returns the currently active spreadsheet, or null if there is none. var currentSheet = SpreadsheetApp.getActive(); var url = currentSheet.getUrl(); Logger.log( url );

google-apps-script • SpreadsheetApp Active Sheet

Docker stats all running containers

sudo docker stats $(sudo docker inspect -f "{{ .Name }}" $(sudo docker ps -q)) Shows live CPU usage of all running containers.

Docker • Docker stats all running containers

Reading from and writing to a file

Before reading and writing text files you should know what encoding to use. See the Perl Unicode Documentation for more details on encoding. Here we show the setting of UTF-8 as the default encoding and decoding for the function open. This is done by using the open pragma near the top of your code (...

Perl Language • File I/O (reading and writing files)

Disabling HTML Import caching

HTML Import caching will sometimes mean that changes made to HTML files that get imported do not get reflected upon browser refresh. Take the following import as an example: <link rel="import" href="./my-element.html"> If a change is done to my-element.html after previo...

polymer • Debugging

Iterating over nodes

The NodeIterator interface provides methods for iterating over nodes in a DOM tree. Given a document like this one: <html> <body> <section class="main"> <ul> <li>List Item</li> <li>List Item</li> <li>Li...

DOM • Traversal

Removing a class

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. * Note class names are not stored in the element's property in any particular order W3C DOM4 Removing one class from an...

DOM • Manipulating a list of CSS classes

Testing for a class

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. * Note class names are not stored in the element's property in any particular order W3C DOM4 Testing if an element cont...

DOM • Manipulating a list of CSS classes

Working with columns containg NULL values

In MySQL and other SQL dialects, NULL values have special properties. Consider the following table containing job applicants, the companies they worked for, and the date they left the company. NULL indicates that an applicant still works at the company: CREATE TABLE example (`applicant_id` INT, `...

MySQL • Dealing with sparse or missing data

Prototype Pattern (C++)

class IPrototype { public: virtual ~IPrototype() = default; auto Clone() const { return std::unique_ptr<IPrototype>{DoClone()}; } auto Create() const { return std::unique_ptr<IPrototype>{DoCreate()}; } private: virtual IPrototype* DoClone() const = 0; virt...

Design patterns • Prototype Pattern

Optimizing Storage Layout for InnoDB Tables

In InnoDB, having a long PRIMARY KEY (either a single column with a lengthy value, or several columns that form a long composite value) wastes a lot of disk space. The primary key value for a row is duplicated in all the secondary index records that point to the same row. Create an AUTO_INCREME...

MySQL • Mysql Performance Tips

Safe reseeding

You may want to re-seed your database without affecting your previously created seeds. For this purpose, you can use firstOrCreate in your seeder: EmployeeType::firstOrCreate([ 'type' => 'manager', ]); Then you can seed the database: php artisan db:seed Later, if you want to add a...

Laravel • Seeding

Rationale

The correct invocation of helper modules and functions can be intimidating because these are generated dynamically (e.g., when creating a new project or adding a new resource) they are not documented explicitly (e.g., MyApp.ErrorHelpers.error_tag) the documentation does not cover all examples (...

phoenix-framework • Generate project documentation

Automatically reload vimrc upon save

To automatically reload vimrc upon save, add the following to your vimrc: if has('autocmd') " ignore this section if your vim does not support autocommands augroup reload_vimrc autocmd! autocmd! BufWritePost $MYVIMRC,$MYGVIMRC nested source % augroup END endif a...

vim • Tips and tricks to boost productivity

Installing Ruby with RVM

The Ruby Version Manager is a command line tool to simply install and manage different versions of Ruby. rvm istall 2.3.1 for example installs Ruby version 2.3.1 on your machine. With rvm list you can see which versions are installed and which is actually set for use. user@dev:~$ rvm li...

Ruby Language • Ruby Version Manager

Adding Siri Extension to App

To integrate Siri capabilities in your app, you should add an extensions as you would do while creating an iOS 10 Widget (old Today View Extension) or a custom keyboard. Adding capability 1- In the project settings, select your iOS app target and go to Capabilities tab 2- Enable the Siri capabili...

iOS • SiriKit

Create an empty dataset based on an existing dataset

Method 1: proc sql; create table foo like sashelp.class; quit; Method 2: proc sql; create table bar as select * from sashelp.class (obs=0); quit; Method 1 should be the preferred option

sas • Proc SQL

Authorizing Contact Access

Importing the framework Swift import Contacts Objective-C #import <Contacts/Contacts.h> Checking accessibility Swift switch CNContactStore.authorizationStatusForEntityType(CNEntityType.Contacts){ case .Authorized: //access contacts case .Denied, .NotDetermined: //request permissio...

iOS • Contacts Framework

Jenkins 2.0+ Pipeline Script

Modern versions of Jenkins (version 2.x) come with a "Build Pipeline Plugin" that can be used to orchestrate complex CI tasks without creating a multitude of interconnected jobs, and allow you to easily version-control your build / test configuration. You may install this manually in a &q...

Django • Continuous Integration With Jenkins

Jenkins 2.0+ Pipeline Script, Docker Containers

Here is an example of a pipeline script that builds a Docker container, then runs the tests inside of it. The entrypoint is assumed to be either manage.py or invoke/fabric with a runtests command available. #!/usr/bin/groovy node { stage 'Checkout' checkout scm sh 'git submodule update ...

Django • Continuous Integration With Jenkins