TypeScript creates single-page weather query applications

This is the 20th day of my participation in the August Text Challenge. For details, see: August Text Challenge.

There are many articles on what TypeScript is. GitHub is a great place to learn about TypeScript. Check out the 7 Popular TypeScript projects on GitHub for some great open source projects. This article uses TypeScript to create a single page application (SPA) example, weather query.

The preparatory work

To complete the sample project, install Node.js and Angular CLI (a command line interface for Angular) :

• Installation Node. Js:

  1. [Download](https://nodejs.org/en/) Suitable version, select the default options to complete the installation.Copy the code

  2. Run the 'node -v' command to verify the version number. The latest version is V10.13.0.Copy the code

• Installing the Angular CLI:

  1. runnpm install -g angular-cliTo install
  2. After successful installation, run the command lineng -vTo view the CLI version

Create the base application and modules

Create an Angular project

Run the following command to generate a new Angular project (where quinwintion-ng-app is the project name) :

ng new quintion-ng-app --skip-git
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Install all the required packages and Angular base applications as follows:

The contents of the qzcloud-ng-app/ SRC directory include:

Run the application:

ng serve
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By default, processes are started on port 4200. You can specify the port number to run by running the ng serve –port 4206 command.

Open your browser and type http://localhost:4206/. The results are shown, indicating that the application is up, running, and ready. Any changes to the project code will automatically restart the project.

Module component code

In fragment 1, line 16 shows the declaration of the AppModule module.

SRC /app/app.module.ts:

This code is automatically generated when the project is created.

import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { AppRoutingModule } from './app-routing.module'; import { AppComponent } from './app.component'; @NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, AppRoutingModule ], providers: [], bootstrap: [AppComponent] // Start Component}) export Class AppModule {}Copy the code

This module contains only one component, AppComponent

Component internal structure

Fragment 2 is the content of the main application component in the SRC /app/app.component.ts file.

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {
  title = 'quintion-ng-app';
}
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Here are the contents of the main application components in the app.component.html file:

<!-- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * -->
<!-- * * * * * * * * * * * The content below * * * * * * * * * * * -->
<!-- * * * * * * * * * * is only a placeholder * * * * * * * * * * -->
<!-- * * * * * * * * * * and can be replaced. * * * * * * * * * * * -->
<!-- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * -->
<!-- * * * * * * * * * Delete the template below * * * * * * * * * * -->
<!-- * * * * * * * to get started with your project! * * * * * * * * -->
<!-- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * -->

<style>
  :host {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    font-size: 14px;
    color: #333;
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
  }

  h1,
  h2,
  h3,
  h4,
  h5,
  h6 {
    margin: 8px 0;
  }

  p {
    margin: 0;
  }

  .spacer {
    flex: 1;
  }

  .toolbar {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 60px;
    display: flex;
    align-items: center;
    background-color: #1976d2;
    color: white;
    font-weight: 600;
  }

  .toolbar img {
    margin: 0 16px;
  }

  .toolbar #twitter-logo {
    height: 40px;
    margin: 0 16px;
  }

  .toolbar #twitter-logo:hover {
    opacity: 0.8;
  }

  .content {
    display: flex;
    margin: 82px auto 32px;
    padding: 0 16px;
    max-width: 960px;
    flex-direction: column;
    align-items: center;
  }

  svg.material-icons {
    height: 24px;
    width: auto;
  }

  svg.material-icons:not(:last-child) {
    margin-right: 8px;
  }

  .card svg.material-icons path {
    fill: #888;
  }

  .card-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    margin-top: 16px;
  }

  .card {
    border-radius: 4px;
    border: 1px solid #eee;
    background-color: #fafafa;
    height: 40px;
    width: 200px;
    margin: 0 8px 16px;
    padding: 16px;
    display: flex;
    flex-direction: row;
    justify-content: center;
    align-items: center;
    transition: all 0.2s ease-in-out;
    line-height: 24px;
  }

  .card-container .card:not(:last-child) {
    margin-right: 0;
  }

  .card.card-small {
    height: 16px;
    width: 168px;
  }

  .card-container .card:not(.highlight-card) {
    cursor: pointer;
  }

  .card-container .card:not(.highlight-card):hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 17px rgba(0, 0, 0, 0.35);
  }

  .card-container .card:not(.highlight-card):hover .material-icons path {
    fill: rgb(105, 103, 103);
  }

  .card.highlight-card {
    background-color: #1976d2;
    color: white;
    font-weight: 600;
    border: none;
    width: auto;
    min-width: 30%;
    position: relative;
  }

  .card.card.highlight-card span {
    margin-left: 60px;
  }

  svg#rocket {
    width: 80px;
    position: absolute;
    left: -10px;
    top: -24px;
  }

  svg#rocket-smoke {
    height: calc(100vh - 95px);
    position: absolute;
    top: 10px;
    right: 180px;
    z-index: -10;
  }

  a,
  a:visited,
  a:hover {
    color: #1976d2;
    text-decoration: none;
  }

  a:hover {
    color: #125699;
  }

  .terminal {
    position: relative;
    width: 80%;
    max-width: 600px;
    border-radius: 6px;
    padding-top: 45px;
    margin-top: 8px;
    overflow: hidden;
    background-color: rgb(15, 15, 16);
  }

  .terminal::before {
    content: "\2022 \2022 \2022";
    position: absolute;
    top: 0;
    left: 0;
    height: 4px;
    background: rgb(58, 58, 58);
    color: #c2c3c4;
    width: 100%;
    font-size: 2rem;
    line-height: 0;
    padding: 14px 0;
    text-indent: 4px;
  }

  .terminal pre {
    font-family: SFMono-Regular,Consolas,Liberation Mono,Menlo,monospace;
    color: white;
    padding: 0 1rem 1rem;
    margin: 0;
  }

  .circle-link {
    height: 40px;
    width: 40px;
    border-radius: 40px;
    margin: 8px;
    background-color: white;
    border: 1px solid #eeeeee;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    transition: 1s ease-out;
  }

  .circle-link:hover {
    transform: translateY(-0.25rem);
    box-shadow: 0px 3px 15px rgba(0, 0, 0, 0.2);
  }

  footer {
    margin-top: 8px;
    display: flex;
    align-items: center;
    line-height: 20px;
  }

  footer a {
    display: flex;
    align-items: center;
  }

  .github-star-badge {
    color: #24292e;
    display: flex;
    align-items: center;
    font-size: 12px;
    padding: 3px 10px;
    border: 1px solid rgba(27,31,35,.2);
    border-radius: 3px;
    background-image: linear-gradient(-180deg,#fafbfc,#eff3f6 90%);
    margin-left: 4px;
    font-weight: 600;
    font-family: -apple-system,BlinkMacSystemFont,Segoe UI,Helvetica,Arial,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol;
  }

  .github-star-badge:hover {
    background-image: linear-gradient(-180deg,#f0f3f6,#e6ebf1 90%);
    border-color: rgba(27,31,35,.35);
    background-position: -.5em;
  }

  .github-star-badge .material-icons {
    height: 16px;
    width: 16px;
    margin-right: 4px;
  }

  svg#clouds {
    position: fixed;
    bottom: -160px;
    left: -230px;
    z-index: -10;
    width: 1920px;
  }


  /* Responsive Styles */
  @media screen and (max-width: 767px) {

    .card-container > *:not(.circle-link) ,
    .terminal {
      width: 100%;
    }

    .card:not(.highlight-card) {
      height: 16px;
      margin: 8px 0;
    }

    .card.highlight-card span {
      margin-left: 72px;
    }

    svg#rocket-smoke {
      right: 120px;
      transform: rotate(-5deg);
    }
  }

  @media screen and (max-width: 575px) {
    svg#rocket-smoke {
      display: none;
      visibility: hidden;
    }
  }
</style>

<!-- Toolbar -->
<div class="toolbar" role="banner">
  <img
    width="40"
    alt="Angular Logo"
    src="data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyNTAgMjUwIj4KICAgIDxwYXRoIGZpbGw9IiNERDAwMzEiIGQ9Ik0xMjUgMzBMMzEuOSA2My4ybDE0LjIgMTIzLjFMMTI1IDIzMGw3OC45LTQzLjcgMTQuMi0xMjMuMXoiIC8+CiAgICA8cGF0aCBmaWxsPSIjQzMwMDJGIiBkPSJNMTI1IDMwdjIyLjItLjFWMjMwbDc4LjktNDMuNyAxNC4yLTEyMy4xTDEyNSAzMHoiIC8+CiAgICA8cGF0aCAgZmlsbD0iI0ZGRkZGRiIgZD0iTTEyNSA1Mi4xTDY2LjggMTgyLjZoMjEuN2wxMS43LTI5LjJoNDkuNGwxMS43IDI5LjJIMTgzTDEyNSA1Mi4xem0xNyA4My4zaC0zNGwxNy00MC45IDE3IDQwLjl6IiAvPgogIDwvc3ZnPg=="
  />
  <span>Welcome</span>
    <div class="spacer"></div>
    <a aria-label="Angular on twitter" target="_blank" rel="noopener" href="https://twitter.com/angular" title="Twitter">
      <svg id="twitter-logo" height="24" data-name="Logo" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 400 400">
        <rect width="400" height="400" fill="none"/>
        <path d="M153.62,301.59c94.34,0,145.94-78.16,145.94-145.94,0-2.22,0-4.43-.15-6.63A104.36,104.36,0,0,0,325,122.47a102.38,102.38,0,0,1-29.46,8.07,51.47,51.47,0,0,0,22.55-28.37,102.79,102.79,0,0,1-32.57,12.45,51.34,51.34,0,0,0-87.41,46.78A145.62,145.62,0,0,1,92.4,107.81a51.33,51.33,0,0,0,15.88,68.47A50.91,50.91,0,0,1,85,169.86c0,.21,0,.43,0,.65a51.31,51.31,0,0,0,41.15,50.28,51.21,51.21,0,0,1-23.16.88,51.35,51.35,0,0,0,47.92,35.62,102.92,102.92,0,0,1-63.7,22A104.41,104.41,0,0,1,75,278.55a145.21,145.21,0,0,0,78.62,23" fill="#fff"/>
      </svg>
    </a>
</div>

<div class="content" role="main">

  <!-- Highlight Card -->
  <div class="card highlight-card card-small">

    <svg id="rocket" alt="Rocket Ship" xmlns="http://www.w3.org/2000/svg" width="101.678" height="101.678" viewBox="0 0 101.678 101.678">
      <g id="Group_83" data-name="Group 83" transform="translate(-141 -696)">
        <circle id="Ellipse_8" data-name="Ellipse 8" cx="50.839" cy="50.839" r="50.839" transform="translate(141 696)" fill="#dd0031"/>
        <g id="Group_47" data-name="Group 47" transform="translate(165.185 720.185)">
          <path id="Path_33" data-name="Path 33" d="M3.4,42.615a3.084,3.084,0,0,0,3.553,3.553,21.419,21.419,0,0,0,12.215-6.107L9.511,30.4A21.419,21.419,0,0,0,3.4,42.615Z" transform="translate(0.371 3.363)" fill="#fff"/>
          <path id="Path_34" data-name="Path 34" d="M53.3,3.221A3.09,3.09,0,0,0,50.081,0,48.227,48.227,0,0,0,18.322,13.437c-6-1.666-14.991-1.221-18.322,7.218A33.892,33.892,0,0,1,9.439,25.1l-.333.666a3.013,3.013,0,0,0,.555,3.553L23.985,43.641a2.9,2.9,0,0,0,3.553.555l.666-.333A33.892,33.892,0,0,1,32.647,53.3c8.55-3.664,8.884-12.326,7.218-18.322A48.227,48.227,0,0,0,53.3,3.221ZM34.424,9.772a6.439,6.439,0,1,1,9.106,9.106,6.368,6.368,0,0,1-9.106,0A6.467,6.467,0,0,1,34.424,9.772Z" transform="translate(0 0.005)" fill="#fff"/>
        </g>
      </g>
    </svg>

    <span>{{ title }} app is running!</span>

    <svg id="rocket-smoke" alt="Rocket Ship Smoke" xmlns="http://www.w3.org/2000/svg" width="516.119" height="1083.632" viewBox="0 0 516.119 1083.632">
      <path id="Path_40" data-name="Path 40" d="M644.6,141S143.02,215.537,147.049,870.207s342.774,201.755,342.774,201.755S404.659,847.213,388.815,762.2c-27.116-145.51-11.551-384.124,271.9-609.1C671.15,139.365,644.6,141,644.6,141Z" transform="translate(-147.025 -140.939)" fill="#f5f5f5"/>
    </svg>

  </div>

  <!-- Resources -->
  <h2>Resources</h2>
  <p>Here are some links to help you get started:</p>

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    <a class="card" target="_blank" rel="noopener" href="https://angular.io/tutorial">
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    </a>

  </div>

  <!-- Next Steps -->
  <h2>Next Steps</h2>
  <p>What do you want to do next with your app?</p>

  <input type="hidden" #selection>

  <div class="card-container">
    <div class="card card-small" (click)="selection.value = 'component'" tabindex="0">
        <svg class="material-icons" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>

      <span>New Component</span>
    </div>

    <div class="card card-small" (click)="selection.value = 'material'" tabindex="0">
        <svg class="material-icons" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>

      <span>Angular Material</span>
    </div>

    <div class="card card-small" (click)="selection.value = 'pwa'" tabindex="0">
        <svg class="material-icons" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>

      <span>Add PWA Support</span>
    </div>

    <div class="card card-small" (click)="selection.value = 'dependency'" tabindex="0">
      <svg class="material-icons" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>

      <span>Add Dependency</span>
    </div>

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      <span>Run and Watch Tests</span>
    </div>

    <div class="card card-small" (click)="selection.value = 'build'" tabindex="0">
      <svg class="material-icons" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>

      <span>Build for Production</span>
    </div>
  </div>

  <!-- Terminal -->
  <div class="terminal" [ngSwitch]="selection.value">
      <pre *ngSwitchDefault>ng generate component xyz</pre>
      <pre *ngSwitchCase="'material'">ng add @angular/material</pre>
      <pre *ngSwitchCase="'pwa'">ng add @angular/pwa</pre>
      <pre *ngSwitchCase="'dependency'">ng add _____</pre>
      <pre *ngSwitchCase="'test'">ng test</pre>
      <pre *ngSwitchCase="'build'">ng build --prod</pre>
  </div>

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    </a>

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<router-outlet></router-outlet>
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metadata

Append metadata with the @Component decorator, accepting a required configuration object that contains the information Angular needs to create and render the Component and its view.

The code in snippet 2 configures three options using @Component:

• selector: A CSS selector that tells Angular to create and insert an instance of the component where the selector tag is found in the parent HTML file
• templateUrl: The HTML file of the component
• styleUrls: component style sheets, such as.scssfile

Component template location

A template is an HTML file that tells Angular how to render a component. The templateUrl property in snippet 2 points to a view called app.component.html.

Data binding within a component

Data binding tells Angular how to render components. In the app.component.ts file, the value of title is set within the class and used in the app.component.html file. Data binding can be one-way or bidirectional. In this case, if the variable is mentioned in double curly braces {{}}, the mapping is one-way. Values are passed from the class to an HTML file.

Customize components and routes

The base application has a module, a component, a class, a template, metadata, and data binding – but it still lacks four other important pieces:

• Multiple components
• routing
• service
• Use of microservices

Next, you will create these custom components. Run the following command:

• ng generate component Menu: Create the Menu component in the AppModule root (in the same folder).
• ng generate component Weather: Create the Weather component in a subfolder named Weather in the AppModule root module.

After execution, app.module.ts will add the contents of four components:

import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; Import {AppRoutingModule} from './app-routing.module'; import {AppRoutingModule} from '. import { AppComponent } from './app.component'; import { MenuComponent } from './menu.component'; import { WeatherComponent } from './weather/weather.component'; @NgModule({ declarations: [ AppComponent, MenuComponent, WeatherComponent ], imports: [ BrowserModule, AppRoutingModule ], providers: [], bootstrap: [AppComponent] }) export class AppModule { }Copy the code

Create routing

To enable Angular to navigate between components, create routes. Overwrite the menu.component.html file with the contents of section 3 so that the HTML contains the correct menu for all components.

Fragments 3:src/app/menu.com ponent. HTML

<div class="row"> <div class="col-xs-12"> <ul class="nav nav-pills"> <li routerLinkActive="active"> <a [routerLink] = "['/weather]" > weather < / a > < / li > < / ul > < / div > < / div >Copy the code

Next, map the URL path to the component. In the root module folder, create the SRC /app/app-routing.module.ts configuration file as follows.

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { WeatherComponent } from "./weather/weather.component";

const routes: Routes = [
  { path: "", redirectTo: "/weather", pathMatch: "full" },
  { path: "weather", component: WeatherComponent }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }
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Modify the content of app.component.html as follows:

<div class="container">
  <app-menu></app-menu>
  <hr>
  <router-outlet></router-outlet>
</div>
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Add routing information to the app.module.ts file as follows:

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

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { MenuComponent } from './menu.component';
import { WeatherComponent } from './weather/weather.component';

@NgModule({
  declarations: [
    AppComponent,
    MenuComponent,
    WeatherComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }
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Run the application again: ng serve, and the result is as follows:

Create a service

Run the following command to create the service

ng generate service Shared
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Add interface query service, need to apply for appID, can go to the weather API website to apply for. The code is as follows:

import { Injectable } from '@angular/core'; import { HttpClient } from '@angular/common/http'; import { throwError as observableThrowError } from 'rxjs'; import { catchError, tap } from 'rxjs/operators'; @Injectable({ providedIn: 'root' }) export class SharedService { weatherURL1 = "https://www.tianqiapi.com/api/?version=v61&appid=45999158&appsecret=WL6GeLkx&cityid="; weatherURL2 = "&city="; totReqsMade: number = 0; constructor(private _http: HttpClient) { } findWeather(cityid, city) { this.totReqsMade = this.totReqsMade + 1; return this._http .get(this.weatherURL1 + cityid + this.weatherURL2 + city) .pipe( tap((response:any) => response), catchError(this.handleError) ) } private handleError(error: any) { return observableThrowError(error.error || 'Server error'); }}Copy the code

• @Injectable() : indicates that the service can be injected into other components
• totReqsMadeThe: variable is declared here to pass its value between the three components. The total number of service requests made to obtain microservice results is tracked.
• Defines the method: findWeather()

Replace weather.component.ts with the following code:

import { Component, OnInit } from '@angular/core'; import { SharedService } from "./.. /shared.service"; @Component({ selector: 'app-weather', templateUrl: './weather.component.html', styleUrls: ['./weather.component.scss'] }) export class WeatherComponent implements OnInit { cityid: string = "101280601"; City: string = "shenzhen "; op_city: string = ""; op_region: string = ""; op_country: string = ""; op_data: string = ""; op_today: string = ""; constructor(public _sharedService: SharedService) {} ngOnInit() {} callWeatherService() { this._sharedService.findWeather(this.cityid, this.city).subscribe( lstresult => { this.op_city = lstresult["city"]; this.op_country = lstresult["country"]; this.op_data = lstresult; Enclosing op_today = [lstresult [" wea "], [lstresult [" tem2] ", "-", lstresult [" tem1 "], "℃]. Join (" ")]. Join (" "); }, error => { console.log("Error. The findWeather result JSON value is as follows:"); console.log(error); }); }}Copy the code

Update the app.module.ts file to add these services:

import { BrowserModule } from "@angular/platform-browser";
import { NgModule } from "@angular/core";
import { FormsModule } from "@angular/forms";
import { HttpModule } from "@angular/http";

import { AppComponent } from "./app.component";
import { MenuComponent } from "./menu.component";
import { WeatherComponent } from "./weather/weather.component";
import { CONST_ROUTING } from "./app.routing";
import { SharedService } from "./shared.service";

@NgModule({
  declarations: [AppComponent, MenuComponent, WeatherComponent, CurrencyComponent, MovieComponent],
  imports: [BrowserModule, FormsModule, HttpModule, CONST_ROUTING],
  providers: [SharedService],
  bootstrap: [AppComponent]
})
export class AppModule {}
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The component view

Now you need to modify the HTML file outside to include calls to these services.

• weather.component.html

<h2> <div class=" col-MD-8 col-md-offset-2"> <div class="form-group"> <input type="text" value="{{this.cityid}}" Class ="form-control" placeholder=" input city ID..." ><br> <input type="text" value="{{this.city}}" class="form-control" placeholder=" > < br > < button type = "button" class = "BTN BTN - the primary" (click) = "callWeatherService ()" > query immediately < / button > < br > < br > < br > < br > < p Class = "well lead" > < I > : < / I > {{enclosing op_city}} {{enclosing op_country}} < br > < I > the weather: < / I > {{enclosing op_today}} < br > < / p > < p class = "text - info" > the weather service request number:  <span class="badge">{{this._sharedService.totReqsMade}}</span> </p> </div> </div>Copy the code

Run the application

Run the application and query shenzhen weather according to the default value

Bootstrap: add a style file to the index.html file in the root directory:

< link rel = "stylesheet" href = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">Copy the code

Instantly beautiful!

After the