AngularJS is what HTML would have been, had it been designed for building web-apps. Declarative templates with data-binding, MVW, MVVM, MVC, dependency injection and great testability story all implemented with pure client-side JavaScript!

Note: This is referring to version 1.x

Table of Contents

Setting ng-model with object-type value for ng-options

With an object, it can be tricky to preselect a default value unless track by is used:

// in controller
$scope.countries = [
  {id: '1', name: 'Malaysia'},
  {id: '2', name: 'Singapore'}
$scope.selectedCountry = null

$http.get('/countries/mine').then((country) => {
  $scope.selectedCountry = country
<!-- in template -->
<select ng-model="selectedCountry" ng-options="c as for c in countries track by"></select>

ng-include is not allowed on elements with ng-switch-when or ng-switch-default

<!-- Error: [$compile:multidir] Multiple directives [ngSwitchDefault, ngInclude] asking for transclusion -->
<div ng-switch-default ng-include='"some/template.html"'></div>

It must be:

<div ng-switch-default>
  <div ng-include='"some/template.html"'></div>

How ng-annotate makes life easier for minification

For Dependency Injection to work properly after minification, we must annotate a controller's dependencies in an extremely tedious way:

angular.module('my_page', [])
.controller('MyPageCtrl', [
  '$scope', '$rootScope', '$location', '$window', '$timeout', 'myService', 'yourService', 'anyService',
  function($scope, $rootScope, $location, $window, $timeout, myService, yourService, anyService) {
    $scope.myName = 'John Cena'

With ng-annotate and its integration with various build tools:

angular.module('my_page', [])
  function($scope, $rootScope, $location, $window, $timeout, myService, yourService, anyService) {
    $scope.myName = 'John Cena'

Custom form validator with NgModelController

Use case: a number input field that ensures that user enters a value greater than 0.00

A combination of HTML5 number input's min and step would work, but it's not compatible everywhere.

For AngularJS, we can create a custom directive for ng-message:

angular.module('greaterThan', [])
.directive('greaterThan', function() {
  return {
    restrict: 'A',
    require: 'ngModel',
    link: function link(scope, el, attrs, ngModel) {
      ngModel.$validators.greaterThan = function(modelValue, viewValue) {
        const value = Number(modelValue || viewValue)
        const minValue = Number(attrs.greaterThan)

        return !isNaN(value) && !isNaN(minValue) ? value > minValue : true

Use it like:

<form name='myForm' novalidate>
  <input type='number' greater-than='0' name='price'>
  <div ng-messages='myForm.price.$error'>
    <div ng-message='greaterThan'>The price must be greater than 0</div>