JavaScript

Angular 9 Tutorial: Project Structure

Pandiyan Murugan1 Comment

In the previous post, we have discussed how to create hello world application in angular. Using Angular CLI, we have generated basic files needed to run a hello world application.

Now, let’s have a quick look at the files and folders in our new Angular project.

The generated projects have the following files and folders structure

The top level of the workspace contains workspace-wide configuration files, configuration files for the root-level application, and subfolders for the root-level application source and test files.

WORKSPACE CONFIG FILESPURPOSE
.editorconfigConfiguration for code editors. See EditorConfig.
.gitignoreSpecifies intentionally untracked files that Git should ignore.
README.mdIntroductory documentation for the root app.
angular.jsonCLI configuration defaults for all projects in the workspace, including configuration options for build, serve, and test tools that the CLI uses, such as TSLint, Karma, and Protractor. For details, see Angular Workspace Configuration.
package.jsonConfigures npm package dependencies that are available to all projects in the workspace. See npm documentation for the specific format and contents of this file.
package-lock.jsonProvides version information for all packages installed into node_modules by the npm client. See npm documentation for details. If you use the yarn client, this file will be yarn.lock instead.
src/Source files for the root-level application project.
node_modules/Provides npm packages to the entire workspace. Workspace-wide node_modules dependencies are visible to all projects.
tsconfig.jsonDefault TypeScript configuration for projects in the workspace.
tslint.jsonDefault TSLint configuration for projects in the workspace.

Application source files

Files at the top level of src/ support testing and running your application. Subfolders contain the application source and application-specific configuration.

APP SUPPORT FILESPURPOSE
app/Contains the component files in which your application logic and data are defined. See details below.
assets/Contains image and other asset files to be copied as-is when you build your application.
environments/Contains build configuration options for particular target environments. By default there is an unnamed standard development environment and a production (“prod”) environment. You can define additional target environment configurations.
favicon.icoAn icon to use for this application in the bookmark bar.
index.htmlThe main HTML page that is served when someone visits your site. The CLI automatically adds all JavaScript and CSS files when building your app, so you typically don’t need to add any <script> or<link> tags here manually.
main.tsThe main entry point for your application. Compiles the application with the JIT compiler and bootstraps the application’s root module (AppModule) to run in the browser. You can also use the AOT compiler without changing any code by appending the --aot flag to the CLI build and serve commands.
polyfills.tsProvides polyfill scripts for browser support.
styles.sassLists CSS files that supply styles for a project. The extension reflects the style preprocessor you have configured for the project.
test.tsThe main entry point for your unit tests, with some Angular-specific configuration. You don’t typically need to edit this file.

Inside the src/ folder, the app/ folder contains your project’s logic and data. Angular components, templates, and styles go here.

SRC/APP/ FILESPURPOSE
app/app.component.tsDefines the logic for the app’s root component, named AppComponent. The view associated with this root component becomes the root of the view hierarchy as you add components and services to your application.
app/app.component.htmlDefines the HTML template associated with the root AppComponent.
app/app.component.cssDefines the base CSS stylesheet for the root AppComponent.
app/app.component.spec.tsDefines a unit test for the root AppComponent.
app/app.module.tsDefines the root module, named AppModule, that tells Angular how to assemble the application. Initially declares only the AppComponent. As you add more components to the app, they must be declared here.

Application configuration files

The application-specific configuration files for the root application reside at the workspace root level. For a multi-project workspace, project-specific configuration files are in the project root, under projects/project-name/.

Project-specific TypeScript configuration files inherit from the workspace-wide tsconfig.json, and project-specific TSLint configuration files inherit from the workspace-wide tslint.json.

APPLICATION-SPECIFIC CONFIG FILESPURPOSE
browserslistConfigures sharing of target browsers and Node.js versions among various front-end tools. See Browserslist on GitHub for more information.
karma.conf.jsApplication-specific Karma configuration.
tsconfig.app.jsonApplication-specific TypeScript configuration, including TypeScript and Angular template compiler options. See TypeScript Configuration and Angular Compiler Options.
tsconfig.spec.jsonTypeScript configuration for the application tests. See TypeScript Configuration.
tslint.jsonApplication-specific TSLint configuration.

Reference

https://angular.io/guide/file-structure

Course Main page

Angular 9 Tutorial for Beginners: Action Plan

ECMAScript – Trailing Commas

Pandiyan MuruganLeave a comment

JavaScript allowed trailing commas in array literals since the beginning. Trailing commas in other places have added in the later edition of ECMAScript.

What is trailing comma & why?

Trailing commas is also called as final commas.

It can be used while if you are adding new parameters or property to JavaScript code. If you want to add a new property, you can simply add a new line without modifying the previously last line if that line already uses a trailing comma. This makes version-control diffs cleaner and editing code might be less troublesome.

Arrays, Object literals, function parameters allow trailing commas. However, JSON doesn’t allow trailing commas.

Trailing commas in Array literals

JavaScript allows the trailing commas in arrays.

literals1

If more than one trailing comma is used, an elision (or hole) is produced. An array with holes is called sparse (a dense array has no holes). When iterating arrays for example with Array.prototype.forEach() or Array.prototype.map(), array holes are skipped.

literals2

However, the final comma in the array is ignored.

Object literals

Trailing comma is supported in Object literals from the ECMAScript 5 edition.

literals3.PNG

Trailing commas in functions

ECMAScript 2017 allows trailing commas in function parameter lists.

Trailing commas allowed function definition and function calls. Trailing commas don’t affect the length property of function declarations or their arguments object.

literals4.PNG

Function parameters with commas only are invalid which will throw SyntaxError.

literals5

What about Internet Explorer Support?

If we are using babel to convert our scripts to native JavaScript to support Internet Explorer. We don’t have to worry about the compatibility.

The babel will convert our scripts with trailing commas to support the IE.

Example: It will remove the commas while building the package.

Left side: Our ECMAScript code

Right side: Equivalent Code generated by babel

literals6.PNG

makes version-control diffs cleaner and editing code might be less troublesome

Let’s talk about the main advantage, the Version control support.

Check out the below sample, I’m trying to add an entry to list to two arrays.

One has trailing commas and other not. When we are adding an entry to an array which has trailing comma, the GIT diff looks clean. That’s the main advantage of this whole concept.

When we are having a trailing comma, it only shows the addition of entry.

gitliteral

 

And again, its based every individual to decide whether they want to use this concept or not.

Cheers,

Happy Coding!