Tutorial by Examples: w

The String object has the following methods that accept regular expressions as arguments. "string".match(... "string".replace(... "string".split(... "string".search(... Match with RegExp console.log("string".match(/[i-n]+/)); console.log(&...

git remote add upstream git-repository-url Adds remote git repository represented by git-repository-url as new remote named upstream to the git repository

You can make Git ignore certain files and directories — that is, exclude them from being tracked by Git — by creating one or more .gitignore files in your repository. In software projects, .gitignore typically contains a listing of files and/or directories that are generated during the build proces...

A basic "Hello, World!" program in Haskell can be expressed concisely in just one or two lines: main :: IO () main = putStrLn "Hello, World!" The first line is an optional type annotation, indicating that main is a value of type IO (), representing an I/O action which "...

Arrays can be created by enclosing a list of elements in square brackets ([ and ]). Array elements in this notation are separated with commas: array = [1, 2, 3, 4] Arrays can contain any kind of objects in any combination with no restrictions on type: array = [1, 'b', nil, [3, 4]]

An empty Array ([]) can be created with Array's class method, Array::new: Array.new To set the length of the array, pass a numerical argument: Array.new 3 #=> [nil, nil, nil] There are two ways to populate an array with default values: Pass an immutable value as second argument. P...

In order to access the value of an Optional, it needs to be unwrapped. You can conditionally unwrap an Optional using optional binding and force unwrap an Optional using the ! operator. Conditionally unwrapping effectively asks "Does this variable have a value?" while force unwrapping sa...

The Promise.all() static method accepts an iterable (e.g. an Array) of promises and returns a new promise, which resolves when all promises in the iterable have resolved, or rejects if at least one of the promises in the iterable have rejected. // wait "millis" ms, then resolve with &quot...

The Promise.race() static method accepts an iterable of Promises and returns a new Promise which resolves or rejects as soon as the first of the promises in the iterable has resolved or rejected. // wait "milliseconds" milliseconds, then resolve with "value" function resolve(va...

Arguments are defined in parentheses after the function name: def divide(dividend, divisor): # The names of the function and its arguments # The arguments are available by name in the body of the function print(dividend / divisor) The function name and its list of arguments are called...

Optional arguments can be defined by assigning (using =) a default value to the argument-name: def make(action='nothing'): return action Calling this function is possible in 3 different ways: make("fun") # Out: fun make(action="sleep") # Out: sleep # The argumen...

One can give a function as many arguments as one wants, the only fixed rules are that each argument name must be unique and that optional arguments must be after the not-optional ones: def func(value1, value2, optionalvalue=10): return '{0} {1} {2}'.format(value1, value2, optionalvalue1) Wh...

Arbitrary number of positional arguments: Defining a function capable of taking an arbitrary number of arguments can be done by prefixing one of the arguments with a * def func(*args): # args will be a tuple containing all values that are passed in for i in args: print(i) fun...

<a href="example.com" target="_blank">Text Here</a> The target attribute specifies where to open the link. By setting it to _blank, you tell the browser to open it in a new tab or window (per user preference). SECURITY VULNERABILITY WARNING! Using target="...

class MyClass { func sayHi() { print("Hello") } deinit { print("Goodbye") } } When a closure captures a reference type (a class instance), it holds a strong reference by default: let closure: () -> Void do { let obj = MyClass() // Captures a strong re...

We have three methods: attr_reader: used to allow reading the variable outside the class. attr_writer: used to allow modifying the variable outside the class. attr_accessor: combines both methods. class Cat attr_reader :age # you can read the age but you can never change it attr_writer...

There is a problem when using optional arguments with a mutable default type (described in Defining a function with optional arguments), which can potentially lead to unexpected behaviour. Explanation This problem arises because a function's default arguments are initialised once, at the point whe...

Python 2.x2.3 raw_input will wait for the user to enter text and then return the result as a string. foo = raw_input("Put a message here that asks the user for input") In the above example foo will store whatever input the user provides. Python 3.x3.0 input will wait for the user ...

Python 2.x2.3 In Python 2.x, to continue a line with print, end the print statement with a comma. It will automatically add a space. print "Hello,", print "World!" # Hello, World! Python 3.x3.0 In Python 3.x, the print function has an optional end parameter that is what...

with open('myfile.txt', 'w') as f: f.write("Line 1") f.write("Line 2") f.write("Line 3") f.write("Line 4") If you open myfile.txt, you will see that its contents are: Line 1Line 2Line 3Line 4 Python doesn't automatically add line b...