Tutorial by Examples: o

Remove, delete and cleanup containers

docker rm can be used to remove a specific containers like this: docker rm <container name or id> To remove all containers you can use this expression: docker rm $(docker ps -qa) By default docker will not delete a container that is running. Any container that is running will produce a...

Docker • Managing containers

normalize.css

Browsers have a default set of CSS styles they use for rendering elements. Some of these styles can even be customised using the browser's settings to change default font face and size definitions, for example. The styles contain the definition of which elements are supposed to be block-level or inl...

CSS • Normalizing Browser Styles

Send text, key pressed and touch events to Android Device via ADB

execute the following command to insert the text into a view with a focus (if it supports text input) 6.0 Send text on SDK 23+ adb shell "input keyboard text 'Paste text on Android Device'" If already connected to your device via adb: input text 'Paste text on Android Device' 6...

Android • adb shell

Reassigning constants

You can't reassign constants. const foo = "bar"; foo = "hello"; Prints: Uncaught TypeError: Assignment to constant.

JavaScript • Declarations and Assignments

Modifying constants

Declaring a variable const only prevents its value from being replaced by a new value. const does not put any restrictions on the internal state of an object. The following example shows that a value of a property of a const object can be changed, and even new properties can be added, because the ob...

JavaScript • Declarations and Assignments

Declaring and initializing constants

You can initialize a constant by using the const keyword. const foo = 100; const bar = false; const person = { name: "John" }; const fun = function () = { /* ... */ }; const arrowFun = () => /* ... */ ; Important You must declare and initialize a constant in the same statement....

JavaScript • Declarations and Assignments

Push a specific object to a remote branch

General syntax git push <remotename> <object>:<remotebranchname> Example git push origin master:wip-yourname Will push your master branch to the wip-yourname branch of origin (most of the time, the repository you cloned from). Delete remote branch Deleting the remote br...

Git • Pushing

Granting & revoking API 23+ permissions

A one-liner that helps granting or revoking vulnerable permissions. granting adb shell pm grant <sample.package.id> android.permission.<PERMISSION_NAME> revoking adb shell pm revoke <sample.package.id> android.permission.<PERMISSION_NAME> Granting all run...

Android • adb shell

Print application data

This command print all relevant application data: version code version name granted permissions (Android API 23+) etc.. adb shell dumpsys package <your.package.id>

Android • adb shell

Hello World

Without JSX Here's a basic example that uses React's main API to create a React element and the React DOM API to render the React element in the browser. <!DOCTYPE html> <html> <head> <meta charset="UTF-8" /> <title>Hello React!</title> ...

React • Getting started with React

Infinity and NaN ("not a number")

In all versions of Python, we can represent infinity and NaN ("not a number") as follows: pos_inf = float('inf') # positive infinity neg_inf = float('-inf') # negative infinity not_a_num = float('nan') # NaN ("not a number") In Python 3.5 and higher, we can also us...

Python Language • Math Module

Iterating over a list

Python supports using a for loop directly on a list: my_list = ['foo', 'bar', 'baz'] for item in my_list: print(item) # Output: foo # Output: bar # Output: baz You can also get the position of each item at the same time: for (index, item) in enumerate(my_list): print('The item i...

Python Language • List

Create a "Please wait..." popup

This code can be added to any event like a listener, button, etc. A blocking JDialog will appear and will remain until the process is complete. final JDialog loading = new JDialog(parentComponent); JPanel p1 = new JPanel(new BorderLayout()); p1.add(new JLabel("Please wait..."), BorderLa...

swing • Basics

Hello World

class Greeter { greeting: string; constructor(message: string) { this.greeting = message; } greet(): string { return this.greeting; } }; let greeter = new Greeter("Hello, world!"); console.log(greeter.greet()); Here we have a class, Gree...

TypeScript • Getting started with TypeScript

Installation or Setup

GitHub is a huge collection of Git repositories. In other words, you can think of GitHub as a collection of many projects! Creating An Account Visit GitHub's main page Here Pick a username, enter in your email address, and pick a secure password and you're ready to go! Useful Tools For Git/...

github • Getting started with github

Encoding/decoding error handling

.encode and .decode both have error modes. The default is 'strict', which raises exceptions on error. Other modes are more forgiving. Encoding >>> "£13.55".encode('ascii', errors='replace') b'?13.55' >>> "£13.55".encode('ascii', errors='ignore') b'13.55' ...

Python Language • Unicode and bytes

File I/O

Files opened in a non-binary mode (e.g. 'r' or 'w') deal with strings. The deafult encoding is 'utf8'. open(fn, mode='r') # opens file for reading in utf8 open(fn, mode='r', encoding='utf16') # opens file for reading utf16 # ERROR: cannot write bytes when a string is expecte...

Python Language • Unicode and bytes

ModelForm Example

Create a ModelForm from an existing Model class, by subclassing ModelForm: from django import forms class OrderForm(forms.ModelForm): class Meta: model = Order fields = ['item', 'order_date', 'customer', 'status']

Django • Forms

Context data

Sometimes, your template need a bit more of information. For example, we would like to have the user in the header of the page, with a link to their profile next to the logout link. In these cases, use the get_context_data method. views.py class BookView(DetailView): template_name = "boo...

Django • Class based views

Form and object creation

Writing a view to create object can be quite boring. You have to display a form, you have to validate it, you have to save the item or return the form with an error. Unless you use one of the generic editing views. app/views.py from django.core.urlresolvers import reverse_lazy from django.views.g...

Django • Class based views