Combining AngularJS and Typescript for Enhanced Scope Functionality

Question

Combining AngularJS and Typescript for Enhanced Scope Functionality

I have decided to shift my approach in writing AngularJS apps from plain JavaScript to using TypeScript as a pre-processor.

One of my challenges lies in merging the two approaches, particularly when dealing with scoped method calls.

Let's take the example of a common menu scenario; I want to highlight a specific menu item that is currently active. The HTML template appears like this:

<ul class="nav navbar-nav">
  ...
  <li ng-class="{active: isSelected('/page1')}"><a href="#/page1">Page 1</a></li>
  ...
</ul>

This requires a scoped function named isSelected. In traditional JavaScript coding, I would define it as follows:

$scope.isSelected = function(path) {
  return $location.path().substr(0, path.length) == path;
}

However, this anonymous function doesn't align well with the class model conventions of TypeScript. In TypeScript, I am inclined to write something like this:

export interface MenuScope extends ng.IScope {
    isSelected(path: String): boolean;
}

export class MenuController {

    location: ng.ILocationService;

    scope: MenuScope;

    constructor($scope: MenuScope, $location: ng.ILocationService) {
        this.scope = $scope;
        this.location = $location;

        this.scope.isSelected = function(path) { return this.isSelected(path) }.bind(this);
    }

    isSelected(path: String): boolean {
        return this.location.path().substr(0, path.length) == path;
    }
}

Here, isSelected belongs to the controller rather than the scope, which makes more sense. However, there is still a dependency on an anonymous method to link the scope and controller together.

Moreover, I had to explicitly bind the context of this in order to access the location service within the implementation of isSelected().

My goal in transitioning to TypeScript was to improve code clarity, but this process of indirection through binding an anonymous function seems counterproductive to that aim.

javascript angularjs typescript

Answer 1

Answer №1

To enhance your coding practices, it is recommended not to store your $scope as a variable within the context of this. Instead, utilize this directly as the $scope. A good way to achieve this is by assigning $scope.vm = this; at the start of the constructor function. This approach ensures that every method and property of the class becomes accessible through the $scope object.

It's important to note that you cannot avoid using this.location = $location in TypeScript due to its syntax requirements.

By the way, incorporating $inject for managing dependencies is also considered best practice.

Answer 2

To enhance your coding practices, it is recommended not to store your $scope as a variable within the context of this. Instead, utilize this directly as the $scope. A good way to achieve this is by assigning $scope.vm = this; at the start of the constructor function. This approach ensures that every method and property of the class becomes accessible through the $scope object.

It's important to note that you cannot avoid using this.location = $location in TypeScript due to its syntax requirements.

By the way, incorporating $inject for managing dependencies is also considered best practice.

Answer 3

Answer №2

Presented here is a straightforward app featuring a controller and a service, following the style I typically use in my projects:

/// <reference path="typings/angularjs/angular.d.ts" />
module App {
    var app = angular.module("app", []);
    app.controller("MainController as vm", Controllers.MainController);
    app.service("backend", Services.Backend);
}

module App.Controllers {
    export class MainController {
        public persons: Models.Person[];

        static $inject = ["$location", "backend"];
        constructor(private $location: ng.ILocationService, private backend: Services.Backend) {
            this.getAllPersons();
        }

        public isSelected(path: string): boolean {
            return this.$location.path().substr(0, path.length) == path;
        }

        public getAllPersons() {
            this.backend.getAllPersons()
                .then((persons) => {
                    this.persons = persons;
                })
                .catch((reason) => console.log(reason));
        }
    }
}

module App.Services {
    export class Backend {
        static $inject = ["$http"];
        constructor(private $http: ng.IHttpService) { }

        public getAllPersons(): ng.IPromise<Models.Person[]> {
            return this.$http.get("api/person")
                .then((response) => response.data);
        }
    }
}

module App.Models {
    export interface Person {
        id: number;
        firstName: string;
        lastName: string;
    }
}

In my setup, I categorize modules into app, controllers, services, and models.
The controller is structured as a class but needs to be linked to the app using controller as syntax. This enables access to everything defined within the class via vm in the view (controller scope), including persons, isSelected, and getAllPersons.
Dependency injection is managed through static $inject with a string[] array, ensuring minifiability and correct parameter order in constructors. This technique applies to services as well.
By injecting $scope into your controller class, you gain access to scope-specific functionalities like $apply and on.
Rather than defining factories, opt for services when you want to define them as classes instead.
The process of injection remains consistent across services and controllers.
To specify the return type of HTTP calls, declare it as ng.IPromise<Model> and return only response.data to maintain entity-based returns free of HTTP-related data.

Answer 4

Presented here is a straightforward app featuring a controller and a service, following the style I typically use in my projects:

/// <reference path="typings/angularjs/angular.d.ts" />
module App {
    var app = angular.module("app", []);
    app.controller("MainController as vm", Controllers.MainController);
    app.service("backend", Services.Backend);
}

module App.Controllers {
    export class MainController {
        public persons: Models.Person[];

        static $inject = ["$location", "backend"];
        constructor(private $location: ng.ILocationService, private backend: Services.Backend) {
            this.getAllPersons();
        }

        public isSelected(path: string): boolean {
            return this.$location.path().substr(0, path.length) == path;
        }

        public getAllPersons() {
            this.backend.getAllPersons()
                .then((persons) => {
                    this.persons = persons;
                })
                .catch((reason) => console.log(reason));
        }
    }
}

module App.Services {
    export class Backend {
        static $inject = ["$http"];
        constructor(private $http: ng.IHttpService) { }

        public getAllPersons(): ng.IPromise<Models.Person[]> {
            return this.$http.get("api/person")
                .then((response) => response.data);
        }
    }
}

module App.Models {
    export interface Person {
        id: number;
        firstName: string;
        lastName: string;
    }
}

In my setup, I categorize modules into app, controllers, services, and models.
The controller is structured as a class but needs to be linked to the app using controller as syntax. This enables access to everything defined within the class via vm in the view (controller scope), including persons, isSelected, and getAllPersons.
Dependency injection is managed through static $inject with a string[] array, ensuring minifiability and correct parameter order in constructors. This technique applies to services as well.
By injecting $scope into your controller class, you gain access to scope-specific functionalities like $apply and on.
Rather than defining factories, opt for services when you want to define them as classes instead.
The process of injection remains consistent across services and controllers.
To specify the return type of HTTP calls, declare it as ng.IPromise<Model> and return only response.data to maintain entity-based returns free of HTTP-related data.

Answer 5

Answer №3

Our team recently contemplated a similar conversion, transitioning from Javascript to Typescript for Angular. During implementation, we noticed certain peculiarities that required adjustment. A quick solution we found was utilizing the controller as syntax, which allows direct exposure of methods on the controller.

<!-- Implementing controller as syntax -->
<div ng-controller="MenuController as menu">
<ul class="nav navbar-nav">
  ...
  <li ng-class="{active: menu.isSelected('/page1')}"><a href="#/page1">Page 1</a></li>
  ...
</ul>
</div>

This approach bypasses the need to bind the scope's method back to the controller. However, there are some drawbacks worth noting:

Direct access to injectables (e.g. $scope, $location) through the controller may lead to potential scope management issues and lack of clarity regarding controller functionality.
The generated code with classes can appear cluttered and less optimized for minification. This tradeoff between familiarity and optimization could potentially affect performance. It's recommended to review the generated code for any optimization opportunities at the Typescript Playground.

Alternatively, you can opt for strongly typed functions instead of using classes:

export function MenuController($scope: MenuScope, $location: ng.ILocationService): any {
    $scope.isSelected = function(path:string): boolean {
      return $location.path().substr(0, path.length) == path;
    }
}

While the return type 'any' doesn't impact Angular's instantiation process, typos in $scope methods could pose debugging challenges. To mitigate this, consider further enhancing your code by incorporating the controller as syntax. Although manual controller instantiation is restricted, Angular manages this aspect automatically.

export interface IMenuController {
    isSelected(path: string): boolean;
}
export function MenuController($location: ng.ILocationService): IMenuController {
    var self:IMenuController = this;

    self.isSelected = function(path:string): boolean {
      return $location.path().substr(0, path.length) == path;
    }

    // Explicitly returning self / this ensures successful compilation
    return self;
}

TL;DR: While the idea of using classes and compile-time type checking holds appeal, it may not seamlessly align with Angular 1.x framework. For better compatibility, stick to strongly typed functions when working with Angular 1.x projects.

Answer 6

Our team recently contemplated a similar conversion, transitioning from Javascript to Typescript for Angular. During implementation, we noticed certain peculiarities that required adjustment. A quick solution we found was utilizing the controller as syntax, which allows direct exposure of methods on the controller.

<!-- Implementing controller as syntax -->
<div ng-controller="MenuController as menu">
<ul class="nav navbar-nav">
  ...
  <li ng-class="{active: menu.isSelected('/page1')}"><a href="#/page1">Page 1</a></li>
  ...
</ul>
</div>

This approach bypasses the need to bind the scope's method back to the controller. However, there are some drawbacks worth noting:

Direct access to injectables (e.g. $scope, $location) through the controller may lead to potential scope management issues and lack of clarity regarding controller functionality.
The generated code with classes can appear cluttered and less optimized for minification. This tradeoff between familiarity and optimization could potentially affect performance. It's recommended to review the generated code for any optimization opportunities at the Typescript Playground.

Alternatively, you can opt for strongly typed functions instead of using classes:

export function MenuController($scope: MenuScope, $location: ng.ILocationService): any {
    $scope.isSelected = function(path:string): boolean {
      return $location.path().substr(0, path.length) == path;
    }
}

While the return type 'any' doesn't impact Angular's instantiation process, typos in $scope methods could pose debugging challenges. To mitigate this, consider further enhancing your code by incorporating the controller as syntax. Although manual controller instantiation is restricted, Angular manages this aspect automatically.

export interface IMenuController {
    isSelected(path: string): boolean;
}
export function MenuController($location: ng.ILocationService): IMenuController {
    var self:IMenuController = this;

    self.isSelected = function(path:string): boolean {
      return $location.path().substr(0, path.length) == path;
    }

    // Explicitly returning self / this ensures successful compilation
    return self;
}

TL;DR: While the idea of using classes and compile-time type checking holds appeal, it may not seamlessly align with Angular 1.x framework. For better compatibility, stick to strongly typed functions when working with Angular 1.x projects.

Combining AngularJS and Typescript for Enhanced Scope Functionality

Answer №1

Answer №2

Answer №3

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