{"id":3818,"date":"2018-08-19T20:26:15","date_gmt":"2018-08-19T14:56:15","guid":{"rendered":"https:\/\/code4developers.com\/?p=3818"},"modified":"2023-10-16T00:02:39","modified_gmt":"2023-10-15T18:32:39","slug":"slicepipe-jsonpipe-asyncpipe","status":"publish","type":"post","link":"https:\/\/code4developers.com\/slicepipe-jsonpipe-asyncpipe\/","title":{"rendered":"Pipes in Angular Part \u2013 4 : SlicePipe, JSONPipe, AsyncPipe"},"content":{"rendered":"<p>Here is the fourth part of angular pipe series in this part we will discuss about <a href=\"https:\/\/code4developers.com\/slicepipe-jsonpipe-asyncpipe\/#SlicePipe\">SlicePipe<\/a>, <a href=\"https:\/\/code4developers.com\/slicepipe-jsonpipe-asyncpipe\/#JSONPipe\">JSONPipe<\/a>, and <a href=\"https:\/\/code4developers.com\/slicepipe-jsonpipe-asyncpipe\/#AsyncPipe\">AsyncPipe<\/a>. If you have not read previous articles here is the link for previous articles.<!--more--><\/p>\n<ul>\n<li><a href=\"https:\/\/code4developers.com\/angular-pipes\/\">Pipes in Angular Part \u2013 1 : lowercase, uppercase, and titlecase pipes<\/a><\/li>\n<li><a href=\"https:\/\/code4developers.com\/datepipe-in-angular\/\">Pipes in Angular Part \u2013 2 : DatePipe<\/a><\/li>\n<li><a href=\"https:\/\/code4developers.com\/currencypipe-percentpipe\/\">Pipes in Angular Part \u2013 3 : CurrencyPipe, PercentPipe<\/a><\/li>\n<\/ul>\n<div>\n<div>\n<div>\n<div><\/div>\n<\/div>\n<h3 id=\"SlicePipe\"><span id=\"slicepipe\">SlicePipe<\/span><\/h3>\n<p>SlicePipe creates the new Array or String containing the subset of given elements. It works same as JavaScript API Array.prototype.slice() and String.prototype.slice()<\/p>\n<p>The slice() with Array returns the selected elements in an array, as a new array object. It will be the copy of the main object event if it is returning whole array.<\/p>\n<p>The slice() with String selects the elements starting at the given start argument, and ends at, but does not include, the given end argument.<\/p>\n<p><strong>Syntax<\/strong><\/p>\n<div>\n<div>{{ value_expression | slice : start [ : end ] }}<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div><\/div>\n<div>Let us consider below example for better understanding of this pipe.<\/div>\n<div><\/div>\n<div><strong>app.component.ts<\/strong><\/div>\n<div>\n<pre class=\"theme:github lang:default decode:true\">import { Component } from '@angular\/core';\r\n\r\n@Component({\r\n  selector: 'app-root',\r\n  templateUrl: '.\/app.component.html',\r\n  styleUrls: ['.\/app.component.css']\r\n})\r\nexport class AppComponent {\r\n  animalArray: string[] = ['Tiger', 'Lion', 'Wolf', 'Elephant', 'Monkey'];\r\n}<\/pre>\n<p><strong>app.component.html<\/strong><\/p>\n<pre class=\"theme:github lang:default decode:true\">&lt;div style=\"text-align:left\"&gt;\r\n  &lt;ul&gt;\r\n    &lt;li *ngFor = \"let obj of animalArray | slice:2:4\"&gt;{{obj}}&lt;\/li&gt;\r\n  &lt;\/ul&gt;\r\n&lt;\/div&gt;\r\n<\/pre>\n<p><strong>Output<\/strong><\/p>\n<ul>\n<li>Wolf<\/li>\n<li>Elephant<\/li>\n<\/ul>\n<p>We can also use this pipe for the string variable. Let us consider very short and quick example<\/p>\n<pre class=\"theme:github lang:default decode:true\">\/\/Component\r\nexport class AppComponent {\r\n  str: string = 'abcdefg';\r\n}\r\n\r\n\/\/HTML\r\n&lt;div style=\"text-align:left\"&gt;\r\n    &lt;p&gt; {{str | slice:2:4}}&lt;\/p&gt;\r\n&lt;\/div&gt;\r\n\r\n\/\/Output: cd<\/pre>\n<h3 id=\"JSONPipe\"><span id=\"jsonpipe\">JSONPipe<\/span><\/h3>\n<p>JSON Pipe is used to convert a value into its JSON format, which is mostly useful in debugging.<\/p>\n<p><strong>Syntax<\/strong><\/p>\n<div>\n<div>{{ value_expression | json }}<\/div>\n<\/div>\n<\/div>\n<div><\/div>\n<div>Consider the below example for the understanding of the usage of this JSON pipe.<\/div>\n<div><\/div>\n<div><strong>app.component.ts<\/strong><\/div>\n<div>\n<pre class=\"theme:github lang:js decode:true\">import { Component } from '@angular\/core';\r\n\r\n@Component({\r\n  selector: 'app-root',\r\n  templateUrl: '.\/app.component.html',\r\n  styleUrls: ['.\/app.component.css']\r\n})\r\nexport class AppComponent {\r\n  obj: object = {name: 'Yatendrasinh', lastName: 'Joddha', Degrees: {Graduations: 'BCA', Masters: 'MCA'}};\r\n}<\/pre>\n<p><strong>app.component.html<\/strong><\/p>\n<pre class=\"theme:github lang:default decode:true\">&lt;div style=\"text-align:left\"&gt;\r\n    &lt;p&gt; {{obj | json}}&lt;\/p&gt;\r\n&lt;\/div&gt;\r\n\r\n\/\/Output: \r\n\r\n{ \"name\": \"Yatendrasinh\", \"lastName\": \"Joddha\", \"Degrees\": { \"Graduations\": \"BCA\", \"Masters\": \"MCA\" } }<\/pre>\n<\/div>\n<h3 id=\"AsyncPipe\"><span id=\"asyncpipe\">AsyncPipe<\/span><\/h3>\n<p>It is used to opens a value from an asynchronous primitive. The async pipe subscribes to an <code><span style=\"font-size: 10.0pt;\">Observable<\/span><\/code> or <code><span style=\"font-size: 10.0pt;\">Promise<\/span><\/code> and returns the latest value it has produced. When a new value is produced, the\u00a0async pipe marks the component to be checked for changes. When the component gets destroyed, the async pipe unsubscribes automatically to avoid possible memory leaks.<\/p>\n<p><strong>Syntax<\/strong><\/p>\n<p>{{ value_expression | async}}<\/p>\n<p><strong>Example<\/strong><\/p>\n<p>This example binds a Promise to the view. Clicking the Resolve button resolves the promise.<\/p>\n<p><strong>app.component.ts<\/strong><\/p>\n<pre class=\"theme:github lang:js decode:true\">import { Component } from '@angular\/core';\r\n\r\n@Component({\r\n  selector: 'app-root',\r\n  templateUrl: '.\/app.component.html',\r\n  styleUrls: ['.\/app.component.css']\r\n})\r\nexport class AppComponent {\r\n  greeting: Promise&lt;string&gt;|null = null;\r\n  arrived: boolean = false;\r\n \r\n  private resolve: Function|null = null;\r\n \r\n  constructor() { this.reset(); }\r\n \r\n  reset() {\r\n    this.arrived = false;\r\n    this.greeting = new Promise&lt;string&gt;((resolve, reject) =&gt; { this.resolve = resolve; });\r\n  }\r\n \r\n  clicked() {\r\n    if (this.arrived) {\r\n      this.reset();\r\n    } else {\r\n      this.resolve !('hi there!');\r\n      this.arrived = true;\r\n    }\r\n  }\r\n}<\/pre>\n<p><strong>app.component.html<\/strong><\/p>\n<pre class=\"theme:github lang:default decode:true\">&lt;div&gt;\r\n    &lt;code&gt;promise|async&lt;\/code&gt;: \r\n    &lt;button (click)=\"clicked()\"&gt;{{ arrived ? 'Reset' : 'Resolve' }}&lt;\/button&gt;\r\n    &lt;span&gt;Wait for it... {{ greeting | async }}&lt;\/span&gt;\r\n&lt;\/div&gt;\r\n<\/pre>\n<h3 id=\"summary\">Summary<\/h3>\n<p>Hope you are in love with reading the content. Don&#8217;t forgot to give your reviews. In next and final article of this series we will have a look on Custom Pipe.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Here is the fourth part of angular pipe series in this part we will discuss about SlicePipe, JSONPipe, and AsyncPipe. 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