Siit saate teada, kuidas oma 20-minutilise esimese nurgarakenduse luua

Angular on JavaScripti raamistik, mille lõin minu Misko Hevery ja haldas Google. See on MVC (Model View Vontroller). Selle kohta lisateabe saamiseks külastage ametlikku lehte.

Praegu on Angulari uusim versioon 5.2.10. On olemas esimene põlvkond 1.x ja teine ​​põlvkond 2.x ning need kaks põlvkonda on oma struktuuri ja meetodite poolest täiesti erinevad. Ärge muretsege, kui tunnete end versiooni suhtes segaduses, sest selles artiklis kasutame teise põlvkonna 2.x-d

Sisukord

  • Üksuse lisamine (vaadake, kuidas vormi nurkadega esitada)
  • Üksuse eemaldamine (vaadake, kuidas nurga all sündmust lisada)
  • Nurgaanimatsioon (saate teada, kuidas komponente animeerida)

Eeldused:

  • Node.js

Kontrollige, kas teie arvutisse on installitud node.js. Lisateave installimise kohta.

  • npm

npm ( sõlmpaketi haldur) on installitud koos Node.js-ga

Kontrollige versiooni node.js :

node -v

npm:

npm -v

Nurga-CLI

Teil peaks olema Angular-CLI uusim versioon. Lisateave Nurga CLI siin , ja leida paigaldus-.

Installige Angular-cli:

npm install -g @angular/cli

Ja lõpuks peaksite olema:

  • Põhiteadmised JavaScripti kohta
  • HTML ja CSS põhialused

Teil ei pea olema mingeid teadmisi nurga kohta.

Nüüd, kui meil on keskkond oma Angulari rakenduse käitamiseks, alustame!

Meie esimese rakenduse loomine

Komponentide loomiseks ja genereerimiseks kasutame nurk-cli. See loob teenuseid, ruuterit, komponente ja direktiive.

Uue Angular-cli abil nurga all oleva projekti loomiseks lihtsalt käivitage:

ng new my-app

Projekt luuakse automaatselt. Loome oma ülesannete rakenduse!

ng new todo-app

Seejärel avage failid tekstiredaktoris. Ma kasutan Sublime teksti, kuid saate valida mis tahes redaktori.

Rakenduse struktuur näeb välja järgmine:

Ärge muretsege, kui olete failides segaduses. Kõik meie tööd asuvad rakenduste kaustas. See sisaldab viit faili:

Märkus: Angular 2 kasutab TypeScripti , mille failid lõpevad laiendiga .ts .

Meie rakenduse jaoks kena liidese loomiseks kasutame Bootstrap 4 raamistikku.

Kaasa Bootstrap CDN sisse index.html :

Käivitage terminalis rakendus:

ng serve

Rakendus töötab // localhost: 4200 /

Kõik on korras ?!

Nüüd teeme HTML-i struktureerimise. Lihtsa vormi loomiseks kasutame Bootstrapi klasse.

app.component.html :

Todo App

Add

In app.component.css :

body{ padding: 0; margin: 0;
}form{ max-width: 25em; margin: 1em auto;}

Nurgas 2 sisendväärtuse hõivamiseks võime kasutada ngModeli direktiivi. Muutuja saab sisestada atribuudina sisendelemendi sisse.

Muutuja atribuudina loomiseks kasutage #, millele järgneb muutuja nimi.

// get the value of the Variable

{{myVariable.value}}

Nüüd saate muutuja „todo”:

{{todo.value}}

Kõik on korras ?!

Nüüd peame sisendist saadud väärtuse salvestama. Saame klassi AppComponent sees luua tühja massiivi rakenduses app.component.ts :

export class AppComponent { todoArray=[] }

Seejärel peame oma nupule lisama kliki sündmuse, mis lükkab jäädvustatud väärtuse „ todoArray ”.

app.component.html :

Add

In app.component.ts :

export class AppComponent { todoArray=[]
addTodo(value){ this.todoArray.push(value) console.log(this.todos) } }
Massiivi väärtuse nägemiseks kasutage konsooli.log (this.todoArray)

Andmete toomine saidilt „todoArray”

Now we have to fetch data stored in “todosArray.” We will use the *ngFor directive to loop through the array and extract the data.

app.component.html:


    
  • {{todo}}

After fetching data:

The data will now be fetched automatically when we click the add button.

Styling the app

I like to use Google-fonts and Material-icons, which are free to use.

Include Google fonts inside app.component.css:

/*Google fonts*/@import url('//fonts.googleapis.com/css?family=Raleway');

And Material-icons inside index.html:

After adding some styling to our app, it will look like this:

To use Material icons:

iconName

Add “delete” and “add” icons in app.component.html:

// put add icon inside "input-group-text" div
add
// and delete icon inside list item 
  • {{todo}}delete
  • For styles in app.component.css:

    /*Google fonts*/@import url('//fonts.googleapis.com/css?family=Raleway');
    body{ padding: 0; margin: 0;
    }form{ max-width: 30em; margin: 4em auto; position: relative; background: #f4f4f4; padding: 2em 3em;}form h1{ font-family: "Raleway"; color:#F97300; }form input[type=text]::placeholder{ font-family: "Raleway"; color:#666; }form .data{ margin-top: 1em;}form .data li{ background: #fff; border-left: 4px solid #F97300; padding: 1em; margin: 1em auto; color: #666; font-family: "Raleway";}form .data li i{ float: right; color: #888; cursor: pointer;}form .input-group-text{ background: #F97300; border-radius: 50%; width: 5em; height: 5em; padding: 1em 23px; color: #fff; position: absolute; right: 13px; top: 68px; cursor: pointer;}form .input-group-text i{ font-size: 2em;}form .form-control{ height: 3em; font-family: "Raleway";}form .form-control:focus{ box-shadow: 0;}

    Our app is almost done, but we need to add some features. A delete functionality should let users click a delete icon and delete an item. It would also be great to have the option to enter a new item with the return key, instead of clicking the add button.

    Deleting items

    To add the delete functionality, we will use the “splice” array method and a for loop. We will loop through “todoarray” and extract the item we want to delete.

    Add a (click) event to delete icon and give it “todo” as parameter :

  • {{todo}} delete
  • In app.component.ts:

    /*delete item*/ deleteItem(){ console.log("delete item") }

    When you click delete, this should show up in the console:

    Now we have to loop through “todoArray” and splice the item we clicked.

    In app.component.ts:

    /*delete item*/ deleteItem(todo){ for(let i=0 ;i<= this.todoArray.length ;i++){ if(todo== this.todoArray[i]){ this.todoArray.splice(i,1) } } }

    The result:

    Awesome ?!!

    Entering to add items

    We can add a submit event to the form:

    (ngSubmit)="TodoSubmit()"

    We need to add the variable “#todoForm” to the form and give it “ngForm” as a value. In this case, we just have one field so we will just get a single value. If we have multiple fields, the submit event will return the values of all the fields in the form.

    app.component.html

    in app.component.ts

    // submit Form todoSubmit(value:any){ console.log(value) }

    Check the console. It will return an object of values:

    So now we have to push the returned value to “todoArray”:

    // submit Form todoSubmit(value:any){ if(value!==""){ this.todoArray.push(value.todo) //this.todoForm.reset() }else{ alert('Field required **') } }

    Here we are ?. The value is inserted without needing to click the add button, just by clicking “enter”:

    One more thing. To reset the the form after submitting, add the “resetForm()” build-in method to submit the event.

    The form will reset after each submit now:

    Adding animations

    I like to add a little touch of animations. To add animation, import the animations components in your app.component.ts:

    import { Component,trigger,animate,style,transition,keyframes } from '@angular/core';

    Then add the animations property to “@component” decorator:

    @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'], animations:[ trigger("moveInLeft",[ transition("void=> *",[style({transform:"translateX(300px)"}), animate(200,keyframes([ style({transform:"translateX(300px)"}), style({transform:"translateX(0)"}) ]))]),
    transition("*=>void",[style({transform:"translateX(0px)"}), animate(100,keyframes([ style({transform:"translateX(0px)"}), style({transform:"translateX(300px)"}) ]))]) ])
    ]})

    Now the items have a nice effect when they’re entered and deleted.

    All the code

    app.component.ts

    import { Component,trigger,animate,style,transition,keyframes } from '@angular/core';
    @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'], animations:[ trigger("moveInLeft",[ transition("void=> *",[style({transform:"translateX(300px)"}), animate(200,keyframes([ style({transform:"translateX(300px)"}), style({transform:"translateX(0)"}) ]))]),
    transition("*=>void",[style({transform:"translateX(0px)"}), animate(100,keyframes([ style({transform:"translateX(0px)"}), style({transform:"translateX(300px)"}) ]))]) ])
    ]})export class AppComponent { todoArray=[]; todo; //todoForm: new FormGroup()
    addTodo(value){ if(value!==""){ this.todoArray.push(value) //console.log(this.todos) }else{ alert('Field required **') } }
    /*delete item*/ deleteItem(todo){ for(let i=0 ;i<= this.todoArray.length ;i++){ if(todo== this.todoArray[i]){ this.todoArray.splice(i,1) } } }
    // submit Form todoSubmit(value:any){ if(value!==""){ this.todoArray.push(value.todo) //this.todoForm.reset() }else{ alert('Field required **') } } }

    app.component.html

    Todo App

    add
    • {{todo}} delete

    app.component.css

    /*Google fonts*/@import url('//fonts.googleapis.com/css?family=Raleway');
    body{ padding: 0; margin: 0;
    }form{ max-width: 30em; margin: 4em auto; position: relative; background: #f4f4f4; padding: 2em 3em; overflow: hidden;}form h1{ font-family: "Raleway"; color:#F97300; }form input[type=text]::placeholder{ font-family: "Raleway"; color:#666; }form .data{ margin-top: 1em;}form .data li{ background: #fff; border-left: 4px solid #F97300; padding: 1em; margin: 1em auto; color: #666; font-family: "Raleway";}form .data li i{ float: right; color: #888; cursor: pointer;}form .input-group-text{ background: #F97300; border-radius: 50%; width: 5em; height: 5em; padding: 1em 23px; color: #fff; position: absolute; right: 13px; top: 68px; cursor: pointer;}form .input-group-text i{ font-size: 2em;}form .form-control{ height: 3em; font-family: "Raleway";}form .form-control:focus{ box-shadow: 0;}

    We are done ?. You can find the files and code on Github.

    See the Demo

    Conclusion

    Angular is easier than you think. Angular is one of the best JavaScript libraries, and it has great support and a nice community. It also has tools that make working with Angular fast and easy, like Angular-cli.

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    Here are some of the best online courses to learn Angular for free:

    Angular 1.x

    • Shaping with Angular
    • Learn Angular

    Nurk 2.x (soovitatav)

    • õppima Angular2 (Coursetro)
    • YouTube'i esitusloend