Tutorial by Examples: en

Delete a document with the property { greetings: 'Whut?' } const MongoClient = require('mongodb').MongoClient; const url = 'mongodb://localhost:27017/test'; MongoClient.connect(url, function (err, db) { if (err) throw new Error(err); db.collection('myCollection').deleteOne(// Delete...

Delete ALL documents with a 'farewell' property set to 'okay'. const MongoClient = require('mongodb').MongoClient; const url = 'mongodb://localhost:27017/test'; MongoClient.connect(url, function (err, db) { if (err) throw new Error(err); db.collection('myCollection').deleteMany(// M...

You can use the plus (+) operator to concatenate strings: 'Dart ' + 'is ' + 'fun!'; // 'Dart is fun!' You can also use adjacent string literals for concatenation: 'Dart ' 'is ' 'fun!'; // 'Dart is fun!' You can use ${} to interpolate the value of Dart expressions within strings. The curly...

# The following shell function will be used to generate completions for # the "nuance_tune" command. _nuance_tune_opts () { local curr_arg prev_arg curr_arg=${COMP_WORDS[COMP_CWORD]} prev_arg=${COMP_WORDS[COMP_CWORD-1]} # The "config" option takes a file arg, so ...

We are so used to the name D3.js that it's possible to forget that D3 is actually DDD (Data-Driven Documents). And that's what D3 does well, a data-driven approach to DOM (Document Object Model) manipulation: D3 binds data to DOM elements and manipulates those elements based on the bounded data. Le...

Arrow functions do not expose an arguments object; therefore, arguments would simply refer to a variable in the current scope. const arguments = [true]; const foo = x => console.log(arguments[0]); foo(false); // -> true Due to this, arrow functions are also not aware of their caller/ca...

C extensions are comprised of two general pieces: The C Code itself. The extension configuration file. To get started with your first extension put the following in a file named extconf.rb: require 'mkmf' create_makefile('hello_c') A couple of things to point out: First, the name hell...

Sun / Oracle releases of Java SE come in two forms: JRE and JDK. In simple terms, JREs support running Java applications, and JDKs also support Java development. Java Runtime Environment Java Runtime Environment or JRE distributions consist of the set of libraries and tools needed to run and mana...

Orthogonal to the JRE versus JDK dichotomy, there are two types of Java release that are widely available: The Oracle Hotspot releases are the ones that you download from the Oracle download sites. The OpenJDK releases are the ones that are built (typically by third-party providers) from the Ope...

A JDK installation and a text editor are the bare minimum for Java development. (It is nice to have a text editor that can do Java syntax highlighting, but you can do without.) However for serious development work it is recommended that you also use the following: A Java IDE such as Eclipse, In...

You can enhance your own classes with generics just like NSArray or NSDictionary. @interface MyClass<__covariant T> @property (nonnull, nonatomic, strong, readonly) NSArray<T>* allObjects; - (void) addObject:(nonnull T)obj; @end

The format statement applies the given format to the specified variable for display purposes only, i.e. the underlying value does not change. data example1 ; Date = '02AUG2016'd ; /* stored as a SAS date, i.e. a number */ Date2 = '31AUG2016'd ; format Date monyy7. Date2 yymmddn8. ; run...

Idiom specific adjustments can be done from C# code, for example for changing the layout orientation whether the view is shown or a phone or a tablet. if (Device.Idiom == TargetIdiom.Phone) { this.panel.Orientation = StackOrientation.Vertical; } else { this.panel.Orientation = Stac...

Adjustments can be done for specific platforms from C# code, for example for changing padding for all the targeted platforms. if (Device.OS == TargetPlatform.iOS) { panel.Padding = new Thickness (10); } else { panel.Padding = new Thickness (20); } An helper method is also availab...

To move to split on left, use <C-w><C-h> To move to split below, use <C-w><C-j> To move to split on right, use <C-w><C-k> To move to split above, use <C-w><C-l>

It's a better experience to open split below and on right set it using set splitbelow set splitright

The function in this example returns true if two line segments are intersecting and false if not. The example is designed for performance and uses closure to hold working variables // point object: {x:, y:} // p0 & p1 form one segment, p2 & p3 form the second segment // Retur...

// [x0,y0] to [x1,y1] define a line segment // [cx,cy] is circle centerpoint, cr is circle radius function isCircleSegmentColliding(x0,y0,x1,y1,cx,cy,cr){ // calc delta distance: source point to line start var dx=cx-x0; var dy=cy-y0; // calc delta distance: line start to e...

// var rect={x:,y:,width:,height:}; // var line={x1:,y1:,x2:,y2:}; // Get interseting point of line segment & rectangle (if any) function lineRectCollide(line,rect){ // p=line startpoint, p2=line endpoint var p={x:line.x1,y:line.y1}; var p2={x:line.x2,y:line.y2}; // to...

For creating your first project in Phoenix framework at this point you should have, Elixir, Erlang, Hex, and the Phoenix archive installed. You should also have PostgreSQL and node.js installed to build a default application. Open terminal or command prompt and go to location on your file system wh...