Tutorial by Examples: d

Unshift Use .unshift to add one or more items in the beginning of an array. For example: var array = [3, 4, 5, 6]; array.unshift(1, 2); array results in: [1, 2, 3, 4, 5, 6] Push Further .push is used to add items after the last currently existent item. For example: var array = [1, 2, 3...

var object = { key1: 10, key2: 3, key3: 40, key4: 20 }; var array = []; for(var people in object) { array.push([people, object[people]]); } Now array is [ ["key1", 10], ["key2", 3], ["key3", 40], ["key4", 20] ] ...

Given the following array var array = [ ["key1", 10], ["key2", 3], ["key3", 40], ["key4", 20] ]; You can sort it sort it by number(second index) array.sort(function(a, b) { return a[1] - b[1]; }) 6 array.sort((a,b) => a[1] - b[1]);...

For security reasons, PowerShell is set up by default to only allow signed scripts to execute. Executing the following command will allow you to run unsigned scripts (you must run PowerShell as Administrator to do this). Set-ExecutionPolicy RemoteSigned Another way to run PowerShell scripts is t...

Success output stream: cmdlet > file # Send success output to file, overwriting existing content cmdlet >> file # Send success output to file, appending to existing content cmdlet 1>&2 # Send success and error output to error stream Error output stream: cmdlet 2&g...

The border-collapse property determines if a tables' borders should be separated or merged. Below an example of two tables with different values to the border-collapse property: The table on the left has border-collapse: separate while the one on the right has border-collapse: collapse. ValueDe...

The border-spacing property determines the spacing between cells. This has no effect unless border-collapse is set to separate. Below an example of two tables with different values to the border-spacing property: The table on the left has border-spacing: 2px (default) while the one on the right ...

struct Square { private(set) var area = 0 var side: Int = 0 { didSet { area = side*side } } } public struct Square { public private(set) var area = 0 public var side: Int = 0 { didSet { area = side*side } ...

class Animal def method_missing(method, *args, &block) "Cannot call #{method} on Animal" end end => Animal.new.say_moo > "Cannot call say_moo on Animal"

class Animal def method_missing(method, *args, &block) say, speak = method.to_s.split("_") if say == "say" speak else super end end end => a = Animal.new => a.say_moo => "moo" => a.shout_moo => NoMethodE...

Python 2.x2.6 The format() method can be used to change the alignment of the string. You have to do it with a format expression of the form :[fill_char][align_operator][width] where align_operator is one of: < forces the field to be left-aligned within width. > forces the field to be righ...

#include <stdio.h> /* for perror(), fopen(), fputs() and fclose() */ #include <stdlib.h> /* for the EXIT_* macros */ int main(int argc, char **argv) { int e = EXIT_SUCCESS; /* Get path from argument to main else default to output.txt */ char *path = (argc > 1...

Debug cargo build Release Building with the --release flag enables certain compiler optimizations that aren't done when building a debug build. This makes the code run faster, but makes the compile time a bit longer too. For optimal performance, this command should be used once a release build ...

CommandDescriptionaAppend text following current cursor positionAAppend text at the end of current lineiInsert text before the current cursor positionIInsert text before first non-blank character of current linegIInsert text in first column of cursor linegiInsert text at same position where it was l...

To run migrations in the test environment, run this shell command: rake db:migrate RAILS_ENV=test 5.0 Starting in Rails 5.0, you can use rails instead of rake: rails db:migrate RAILS_ENV=test

To add a new column name to the users table, run the command: rails generate migration AddNameToUsers name This generates the following migration: class AddNameToUsers < ActiveRecord::Migration[5.0] def change add_column :users, :name, :string end end When the migration name i...

To add a new indexed column email to the users table, run the command: rails generate migration AddEmailToUsers email:string:index This will generate the following migration: class AddEmailToUsers < ActiveRecord::Migration[5.0] def change add_column :users, :email, :string add_i...

To add a reference to a team to the users table, run this command: $ rails generate migration AddTeamRefToUsers team:references This generates the following migration: class AddTeamRefToUsers < ActiveRecord::Migration[5.0] def change add_reference :users, :team, foreign_key: true ...

To add multiple columns to a table, separate field:type pairs with spaces when using rails generate migration command. The general syntax is: rails generate migration NAME [field[:type][:index] field[:type][:index]] [options] For example, the following will add name, salary and email fields to ...

Say you want to perform in action (in this case, logging "Foo"), while doing something else (logging "Bar"). Normally, if you don't use concurrency, one of these actions is going to be fully executed, and the other run will run only after it's completely finished. But with concur...