Starting Angular 4

A short guide to angular4 with insights on production & performance.

01 | Template on Plunker

02 | Setup a project locally using ng-cli

if you already have an older version:

npm uninstall -g angular-cli 

npm cache clean

npm install -g @angular/cli@latest

03 | Configure Routes

WARNING! AppComponent Shouldn't be part of routing. But it is set as the default route by ng-cli.

> Never Use this:

{ path: '', component: AppComponent },

> Should use something like below:

import { Routes } from '@angular/router';
import { AppComponent } from './';
import { ContactComponent } from './contact/contact.component';
import { AboutComponent } from './about/about.component';

export const routes: Routes = [
  { path: '', redirectTo: '/contact', pathMatch: 'full' },
  { path: 'contact',  component: ContactComponent },
  { path: 'about',  component: AboutComponent },
  { path: '**', redirectTo: '/contact', pathMatch: 'full' },
];

04 | Routing

From Template:

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From your .ts file (typescript):

// src/app/landing/landing.component.ts
import { Component } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { Router } from '@angular/router';
 
@Component({
  selector: 'app-root',
  templateUrl: './landing.component.html',
  styleUrls: ['./landing.component.css']
})
export class LandingComponent {
  title = 'landing page';
  constructor(private router: Router) {}
 
  launchHome(): void {
    this.router.navigate(['/home']);
  }
}

05 | Barrel Files for the rescue

One of the first things you will notice when you start working on it is, you have to write so many import statements. Gets worst, when you have to make 2 dedicated imports to get hold of 2 components sitting inside the same folder. Well, this isn't one of those where you blame at Angular! This is something to do with Typescript. The resolution is to use barrel files. As a practice you can start creating an index.ts file in each of your folders containing services, components or feature modules. Assume you src folder has too many components (example: Home, About, Contact):

The barrel file:

// src/app/index.ts
export { AppComponent } from './app.component';
export { HomeComponent } from './home.component';
export { AboutComponent } from './about.component';
export { ContactComponent } from './contact.component';

Usage:

import { AppComponent, HomeComponent, AboutComponent, ContactComponent} form './';

// or even simpler
import { * } from './';

There is a neat blog on this which can give you a better understanding of this.

06 | Running the App

ng serve

and navigate your browser to http://localhost:4200

07 | Unit Test and other CI/CD Concerns

There are scripts setup on package.json for these, one can refer it. For more on configuring karma & etc read this blog. Example, Running unit tests (jasmine - BDD):

ng test

08 | Need to create your feature module?

After sometime you realize your app module has grown out of proportion. It is time to consider some logical organization of your code. First is to consider organizing them into modules. Here is a neat read

09 | Adding a Simple Form

You will notice I've placed a simple form in ContactComponent. At this point it's important that you don't forget to import FormsModule in your app.module.ts. However, one thing you will notice there is a realtime representation of form data. It is quite useful for you to debug, it can be achieved with the following peace of markup:


  ...

 
Formdata in realtime:
  {{ form.value | json }}

10 | Lifecycle Hooks

Intention behind post was to have an Angular2 guide which would help one to start a project from scratch & take it all way to deployment. I haven't covered much of Angular2 concepts or structs on this post for brevity & aligning with my intention to keep it super short. However, Lifecycle Hooks are a thing it can't afford to miss. Angular2 provides 8 of them in total: ngOnInit, ngOnChanges, ngDoCheck, ngAfterContentInit, ngAfterContentChecked, ngAfterViewInit, ngAfterViewChecked, ngOnDestroy.

Here is an example:

import { Component, OnInit, OnDestroy } from '@angular/core';
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html'
})
export class AppComponent implements OnInit, OnDestroy {
  constructor() {}
 
  ngOnInit() {
    console.log('App Component Init');
  }
 
  ngOnDestroy() {
    console.log('App Component Destroyed');
  }
}

You can refer this blog if you want to know them in detail

11 | Before you go for Production

You are just a command away if you want to do a production build for your awesome app. Afterwards you just need to copy the generated dist folder to your live server.

ng build --aot --environment prod

Yet, there are few things one should know going to this step. When you execute above the step there are so many things happening behind the scene. Here are some, concatenation, minification, uglification & tree shaking. Since I have already made a note on first 3 on a different blog, I would like you to come to terms with Tree Shaking. Tree Shaking is the process of getting rid of dead code. If you're coming from Java world or most other OOP environments, you will be familiar with a warning called 'unused code/method'. However, if you want to go deep into it with examples & numbers here is great post from an expert. Minko Gechev is the author of the official Angular Style Guide. If you are already an expert at Angular & came across this post whilst considering ways to improve the page load time & performance tuning for your app here is a great stack overflow thread which you shouldn't miss!

12 | Sourcecode

Here is the github repo used for this post.

Tags: angular angular-cli typescript routing barrel-files lifecycle-hooks feature-modules tree-shaking
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