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Create the App | Angular Todos

Table of Contents

Step 1 - Creating a new directory

@angular/cli will create a new directory for our frontend application as well as handle the heavy lifting of configuring all of our build tools.

  1. Create a new folder to contain the frontend, and eventually the backend, application. Open a terminal window, navigate to the new folder, and run the commands:
npm i -g @angular/cli
ng new web -g -S --routing false --style css

The above command creates a new Angular application with the following configuration:

  • Without initiating git (-g skips initiating git)
  • Without creating testing files (-S skips initiating test files)
  • Without setting up routing (--routing false tells the CLI not to setup the routing module)
  • With using CSS as the styling language (--style css tells the CLI to use CSS)
  1. Next create a package.json file and copy into it the following:
{
"scripts": {
"start": "npm --prefix web start",
"postinstall": "npm i --prefix web"
}
}
  1. Then create a .gitignore file and copy into it the following:
/node_modules
  1. Finally return to the terminal and run the command:
npm run start

You'll be greeted by the following screen:

@angular/cli result

Step 2 - Starting with a blank canvas

While the introductory application is nice, we'll want to start with a blank canvas.

  1. Open up the root directory in the IDE of your choice.

  2. Open web/src/styles.css and replace the content of this file with the following:

web/src/styles.css

:root {
--spacing: 4px;
--font-size: 20px;
--on-primary: #ffffff;
--on-secondary: #ffffff;
--primary: #f44336;
--secondary: #2196f3;
--text: #212121;
}

app-task {
display: contents;
}

body {
margin: 0;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto",
"Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans",
"Helvetica Neue", sans-serif;
-webkit-font-smoothing: antialiased;
-moz-osx-font-smoothing: grayscale;
}

button {
border: none;
background-color: var(--secondary);
color: var(--on-secondary);
font-size: var(--font-size);
height: 60px;
margin: var(--spacing) 0;
max-width: 450px;
width: 100%;
}

button[type="submit"] {
background-color: var(--primary);
color: var(--on-primary);
text-transform: uppercase;
}

button:hover {
filter: brightness(80%);
}

button:active {
filter: brightness(120%);
}

code {
font-family: source-code-pro, Menlo, Monaco, Consolas, "Courier New",
monospace;
}

form {
align-items: center;
display: flex;
flex-direction: column;
margin: var(--spacing) 0;
padding: calc(4 * var(--spacing));
}

input {
background: transparent;
border: 1px solid var(--text);
border-radius: 3px;
line-height: 30px;
font-size: var(--font-size);
margin: var(--spacing) 0;
max-width: 416px;
padding: calc(4 * var(--spacing));
width: 100%;
}

input[type="checkbox"] {
height: 48px;
margin: var(--spacing);
width: 48px;
}

li {
display: flex;
height: calc(48px + calc(2 * var(--spacing)));
max-width: 450px;
width: 100%;
}

li.completed {
text-decoration: line-through;
}

span {
flex: 1;
font-size: var(--font-size);
line-height: calc(48px + calc(2 * var(--spacing)));
}

ul {
align-items: center;
display: flex;
flex-direction: column;
list-style-type: none;
padding: calc(4 * var(--spacing));
}
  1. Then open web/src/app/app.component.html and delete all the content in this file.

Step 3 - Adding our components

To build this todo list app, we'll need a few components.

Task

Our first component will be used to render an individual task. We'll bind it to an @Input() element and an @Output() event:

  • @Input() task - The task object itself. It has the following properties:
    • text - A string of the task itself.
    • completed - A boolean property that tracks if a task is completed.
    • id - A unique number to identify a task.
  • @Output() completed - This event emitter will trigger a user taps on the checkbox, emitting the completed task id, and eventually toggling the state of the task.

In your terminal navigate to the web directory and run:

ng g c task

For the logic, replace the content of the TypeScript file with the following:

web/src/app/task/task.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
selector: 'app-task',
templateUrl: './task.component.html',
styleUrls: ['./task.component.css']
})
export class TaskComponent {
@Input() task: any = {};
@Output() completed = new EventEmitter<any>();
}

For the template, add the following code into the HTML file:

web/src/app/task/task.component.html

<li [class.completed]="task.completed">
<span>{{task.text}}</span>
<input type="checkbox" [checked]="task.completed" (click)="completed.emit(task?.id)" readOnly />
</li>

Tasks

Our second component will be used to render a list of tasks. We'll bind it to an @Input() element and an @Output() event:

  • @Input() tasks - An array of tasks.
  • @Output() completed - This event emitter will trigger a user taps on the checkbox in the Task component, bubbling the event up to the AppComponent, and eventually will toggle the state of the task.

In your terminal navigate to the web directory and run:

ng g c tasks

For the logic, replace the content of the TypeScript file with the following:

web/src/app/tasks/tasks.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
selector: 'app-tasks',
templateUrl: './tasks.component.html',
styleUrls: ['./tasks.component.css']
})
export class TasksComponent {
@Input() tasks: any[] = [];
@Output() completed = new EventEmitter<any>();
}

For the template, add the following code into the HTML file:

web/src/app/tasks/tasks.component.html

<ul>
<app-task *ngFor="let task of tasks" [task]="task" (completed)="completed.emit($event)"></app-task>
</ul>

CreateTask

The final component will be a form to allow users to create a new task. We'll bind it to an @Output() event:

  • @Output() addTask - This event emitter will trigger on submission of the form and emits the new task they want to create.

Since we are working with a form element, we will need to add the ReactiveFormsModule to the AppModule. In web/src/app/app.module.ts make the following changes:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
+ import { ReactiveFormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { TaskComponent } from './task/task.component';
import { TasksComponent } from './tasks/tasks.component';

@NgModule({
declarations: [
AppComponent,
TaskComponent,
TasksComponent
],
imports: [
- BrowserModule
+ BrowserModule,
+ ReactiveFormsModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }

In your terminal navigate to the web directory and run:

ng g c create-task

For the logic, replace the content of the TypeScript file with the following:

web/src/app/create-task/create-task.component.ts

import { Component, Output, EventEmitter } from '@angular/core';
import { FormBuilder } from '@angular/forms';

@Component({
selector: 'app-create-task',
templateUrl: './create-task.component.html',
styleUrls: ['./create-task.component.css']
})
export class CreateTaskComponent {
@Output() addTask = new EventEmitter<string>();

createTaskForm = this.fb.group({
task: ''
});

constructor(private fb: FormBuilder) { }

onSubmit() {
if (!this.createTaskForm.valid) return;
this.addTask.emit(this.createTaskForm.value.task as string);
this.createTaskForm.reset();
}
}

For the template, add the following code into the HTML file:

web/src/app/create-task/create-task.component.html

<form [formGroup]="createTaskForm" (ngSubmit)="onSubmit()">
<input
type="text"
placeholder="TODO"
formControlName="task"
required
/>
<button type="submit">Add</button>
</form>

Step 4 - Putting it together

With our different components created, we'll next put them together and see how they work!

  1. Open up web/src/app/app.component.ts and in the AppComponent class we will want to create our tasks array and remove title.

    export class AppComponent {
    - title = 'web';
    + tasks: any[] = [];
  2. We'll also want ways to add and toggle the state of tasks.

    export class AppComponent {
    tasks: any[] = [];

    + createTask(text: string) {
    + return {
    + id: this.tasks.length,
    + text,
    + completed: false,
    + };
    + }
    +
    + addTask(task: string) {
    + const newTask = this.createTask(task);
    + this.tasks.push(newTask);
    + };
    +
    + completed(id: number) {
    + const i = this.tasks.findIndex((t) => t.id === id);
    + this.tasks[i].completed = !this.tasks[i].completed;
    + };
    }
  3. With all of our logic and components in place, we'll finally render our components! Copy the following HTML into web/src/app/app.component.html so we can see our tasks list and add tasks to that list.

    <app-create-task (addTask)="addTask($event)"></app-create-task>
    <app-tasks [tasks]="tasks" (completed)="completed($event)"></app-tasks>
  4. Go to GitHub and create a new repository.

  5. Run the following commands in the working folder.

git init
git add .
git commit -m "first commit"
git branch -M main
  1. Finally, set your remote origin URL and push up the code.

Step 5 - Wrap Up

Go ahead and try adding tasks or marking them as complete.

a working todo list app

The only problem is that these tasks aren't being saved anywhere, so when you refresh the page poof they're gone. In our next step, we will create our backend with Amplication to be able to save our tasks to a database!

To view the changes for this step, visit here.