Error-first callback in node.js

September 19, 2017 superadmin 0

The “error-first” callback is nothing but a standard protocol for Node callbacks. Error-first callbacks are used to pass errors and data as well. The “error-first” callback has a simple rule that the first argument for the callback function should be an error object and it has to be checked to see if something went wrong. Additional arguments are used to pass data. fs.readFile(“./test.php”, function(err, data) { if (err) { // handle the error, the return is important here // so execution stops here return console.log(err) } // use the data object console.log(data) }) As you can see in the above [...]

What is Callback hell in Node.JS

September 19, 2017 superadmin 0

Callback hell “refers to heavily nested callbacks that have become unreadable. To fix this we can break callbacks into independent functions that is referred as modularization. An Example of heavily nested code is below: query(“SELECT userId FROM userss WHERE userName=’jhon’;”, function(id){ query(“SELECT * FROM articles WHERE articleId=” + id, function(articles){ articles.each(function(article){ query(“UPDATE articles SET status = ’0′ WHERE id=” + article.id, function(error){ if(!error){ console.log(“success!!”); }else{ console.log(“error”); } }); }); }); }); To fix this, the above callbacks are broken out into independent functions which can be called with some parameters. var logError = function(error){ if(!error){ console.log(“success!!”); }else{ console.log(“error”); } }, [...]

How to install Angular 2 And Other Dependencies

September 13, 2017 superadmin 0

To start working with Angular 2, you need to do the below steps: Installation steps: 1. Npm: This is known as the node package manager that is used to work with the open source repositories. Angular JS has dependencies on other components. And npm can be used to download these dependencies and attach them to your project. The best way to install npm is to install node using the node.js installer. npm is installed as part of node. 2. Go to Node js official website and choose the installer to download, depending on the operating system. For the purpose of [...]

What is AOT Compilation in Angularjs 2

September 13, 2017 superadmin 0

AOT (Ahead of Time compilation) is used to compiles the angular components and templates to native JavaScript and HTML during the build time instead of run-time. The compiled HTML and JavaScript are deployed to the web server so that the compilation and render time can be saved by the browser. So It is the biggest advantage of AOT to improve the performance of applications. Advantages: Smaller Angular framework download size:  The Angular 2 app is already compiled so it is faster. Faster Rendering: The browser downloads a pre-compiled version of the application. So the browser loads already executable code and [...]

Advantages of angularjs 2 over angular 1

September 13, 2017 superadmin 0

The main differences and advantages on Angular2 vs. Angular 1 as following: It is entirely component based: The earlier version of Angular had a focus of Controllers but now has changed the focus to having components over controllers. Angular 1: var app = angular.module(“userApp”, []); app.controller(“userController”, function($scope) { $scope.users = [{ name: "sathish", Age:30}, { name: "ram", Age:33}]; }); Angular 2: Here the @Component annotation is used to add the metadata to the class. import { Component } from ‘angular2/core’; @Component({ selector: ‘usersdata’, template: ‘<h3>{{users.name}}</h3gt;’ }) export class UsersComponent { users = [{ name: “sathish”, Age:30}, { name: “ram”, Age:33 [...]

What is angular js 2

September 13, 2017 superadmin 0

Angular 2 is an open source JavaScript framework to build client applications in HTML and JavaScript. Angular 2 is so simpler, faster, modular and instrumented design. Angular 2 is a most popular framework for developing mobile applications as well as desktop applications.The “Angular 2″ is using “Traceur” compiler and it takes “ES6″ and compiles it down (ES5) to regular JavaScript that runs in your browsers. It supports following modern browsers are: 1. Chrome 2. Firefox 3. Opera 4. Safari 5. IE Version10, 11 and so on…