JavaScript Style Guide

JavaScript Programming Language

Dynamic
Object-oriented (prototype-based)
Scripting

Client-side

Server-side

JavaScript Style Guide

Elegant syntax

About parens, braces and linebreaks.

1.
if ( condition ) {
  // statements
}

Use whitespace to promote readability

2.
while ( condition ) {
  // statements
}

4.
for ( var i = 0; i < 100; i++ ) { 
  // statements
}

3.
if ( condition ) {
  // statements
} else {
  // statements
}

JavaScript Style Guide

Elegant syntax

About assignments, declarations and functions.

var test = "";
var bar = {};
var foo = [];

Using only one `var` per scope (function)

var test = "",
    bar = {},        
    foo = [];

function foo() {
  // statements here

  var test = "",
      bar;
}

function foo() {
  var test = "",
      bar;

  // statements here
}

JavaScript Style Guide

Elegant syntax

1.
foo(function() {
  // statement
});

Some exceptions

3.
foo([ "Apple", "Samsung" ]);

2.
foo({ 
  name: "Mike",
  Age: 23
});

4.
foo("Apple");

5.
if ( (foo in bar) ) {
  // statement
}

JavaScript Style Guide

Quotes

There is not difference in how JavaScript parses them

"What ABSOLUTELY MUST be enforced is consistency. Never mix quotes in the same project."

JavaScript Style Guide

End of lines and empty lines

Whitespaces can ruin git diffs

JavaScript Style Guide

Type checking

1. typeof variable === "string"

2. typeof variable === "number"

3. typeof variable === "boolean"

4. typeof variable === "object"

7. variable === null

8. variable == null

5. typeof variable === "undefined"

6. variable === undefined

"1" === 1 // false

"1" == 1 // true

JavaScript Style Guide

Conditional Evaluation

1. if ( array.length > 0 )

2. if ( array.length === 0 )

3. if ( string !== "" )

5. if ( foo === true )

6. if ( foo === false )

if ( array.length )

if ( !array.length )

if ( string )

4. if ( string === "" )

if ( !string )

if ( foo )

if ( !foo )

JavaScript Style Guide

Naming

1. functionNamesLikeThis; // camelCase

2. variableNamesLikeThis; // camelCase

4. CONSTANTS_LIKE_THIS; // UPPERCASE

3. ConstructorNamesLikeThis; // PascalCase

JavaScript Style Guide

Naming

If your not a human code compiler, please don't try to be one

function q(s) {
  return document.querySelectorAll(s);
}

var i,a=[],els=q("#foo");
for(i=0;i<els.length;i++){a.push(els[i]);}

function query(selector) {
  return document.querySelectorAll(selector);
}

var elements = [],
    matches = query("#foo"),
    length = matches.length;

for ( var i = 0; i < length; i++ ) {
  elements.push( matches[i] );
}

AngularJS Style Guide

AngularJS

Framework MVC JavaScript

AngularJS Style Guide

Modules

var app = angular.module('app', [
    'ngAnimate',
    'ngRoute'
]);

Definition

angular
    .module('app', [
        'ngAnimate',
        'ngRoute'
    ]);

Avoid

Recommended

AngularJS Style Guide

Modules

var app = angular.module('app');
app.controller('SomeController', SomeController);

function SomeController() { }

Getters

Avoid

Recommended

angular
    .module('app')
    .controller('SomeController', SomeController);

function SomeController() { }

AngularJS Style Guide

Modules

angular
    .module('app')
    .controller('Dashboard', function() { })
    .factory('logger', function() { });

Named vs Anonymous Functions

Avoid

Recommended

angular
    .module('app')
    .controller('Dashboard', Dashboard);

function Dashboard() { }

AngularJS Style Guide

Controllers

<div ng-controller="Customer">
    {{ name }}
</div>

ControllerAs - View syntax

Avoid

Recommended

<div ng-controller="Customer as customer">
    {{ customer.name }}
</div>

AngularJS Style Guide

Controllers

function Customer($scope) {
    $scope.name = {};
    $scope.sendMessage = function() { };
}

ControllerAs - Controller syntax

Avoid

Recommended

function Customer() {
    this.name = {};
    this.sendMessage = function() { };
}

AngularJS Style Guide

Controllers

function Customer() {
    this.name = {};
    this.sendMessage = function() { };
}

ControllerAs with vm

Avoid

Recommended

function Customer() {
    var vm = this;
    vm.name = {};
    vm.sendMessage = function() { };
}

AngularJS Style Guide

Controllers

function Order($http, $q, config, userInfo) {
    var vm = this;
    vm.checkCredit = checkCredit;
    vm.isCreditOk;
    vm.total = 0;

    function checkCredit() {
        var settings = {};
        
        return $http.get(settings)
            .then(function(data) {
               vm.isCreditOk = vm.total <= maxRemainingAmount
            })
            .catch(function(error) {
               // Re-reject with appropriate error for a user to see
            });
    };
}

Defer Controller Logic to Services

Avoid

AngularJS Style Guide

Controllers

function Order(creditService) {
    var vm = this;
    vm.checkCredit = checkCredit;
    vm.isCreditOk;
    vm.total = 0;

    function checkCredit() {
       return creditService.isOrderTotalOk(vm.total)
         .then(function(isOk) { vm.isCreditOk = isOk; })
           .catch(showServiceError);
    };
}

Defer Controller Logic to Services

Recommended

AngularJS Style Guide

Services and Factories

angular
    .module('app')
    .service('logger', logger);

function logger() {
  this.logError = function(msg) {
    /* */
  };
}

Defer Controller Logic to Services

Service

angular
    .module('app')
    .factory('logger', logger);

function logger() {
    return {
        logError: function(msg) {
          /* */
        }
   };
}

Factory

AngularJS Style Guide

Directives

angular
    .module('app.widgets')

    /* directiva de órdenes que es específica del módulo de órdenes*/
    .directive('orderCalendarRange', orderCalendarRange)

    /* directiva de ventas que puede ser usada en algún otro lado a lo
    largo de la aplicación de ventas */
    .directive('salesCustomerInfo', salesCustomerInfo)

    /* directiva de spinner que puede ser usada a lo largo de las
    aplicaciones */
    .directive('sharedSpinner', sharedSpinner);

Limit 1 Per File

Avoid

AngularJS Style Guide

Directives

Limit 1 Per File

Manipulate DOM in a Directive.
Provide a Unique Directive Prefix. (esvyda-)
ControllerAs.
Restrict to Elements and Attributes.

3. 
var directive = {
    restrict: 'EA',
    templateUrl: 'exampleDirective.html',
    controller: ExampleController,
    controllerAs: 'vm',
};

4. 
<div class="my-calendar-range"></div>

Avoid

Recommended

4. 
<my-calendar-range></my-calendar-range>
<div my-calendar-range></div>

AngularJS Style Guide

Manual annotating for Dependency Injection

Manually Identify Dependencies

angular
    .module('app')
    .controller('Dashboard',
        ['$location', '$routeParams', 'common', 'dataservice',
            function Dashboard($location, $routeParams, common, dataservice) {}
        ]);

Avoid

Recommended

angular
    .module('app')
    .controller('Dashboard', Dashboard);

Dashboard.$inject = ['$location', '$routeParams', 'common', 'dataservice'];

function Dashboard($location, $routeParams, common, dataservice) {
}

AngularJS Style Guide

Testing

Unit testing helps maintain clean code

Testing Library

Test Runner

AngularJS Style Guide

Comments

Use JSDoc and JSHint

/**
 * @name logError
 * @desc Logs errors
 * @param {String} msg Message to log
 * @returns {String}
 * @memberOf Factories.Logger
 */
 function logError(msg) {
   var loggedMsg = 'Error: ' + msg;
   $log.error(loggedMsg);
   return loggedMsg;
 };

JSDoc syntax

AngularJS

JavaScript

https://github.com/johnpapa/angular-styleguide/

AngularJS Sytle Guide

https://github.com/rwaldron/idiomatic.js

JavaScript Sytle Guide

http://usejsdoc.org/

JSDoc

http://jshint.com/

JSHint