AngularJS is a JavaScript framework that can be added to HTML page using <script> tag.
AngularJS Usages
- Client side JavaScript Framework.
- Extend HTML so you can create more dynamic contents
Declarative vs Imperative
There are two main programming paradigms used in programming as imperative programming and declarative programming.
- Declarative: Tells you what to do
- You use the declared functions by someone for your needs
- Imperative: Tells you how to do
- You develop the functionalities for your needs
AngularJS is both declarative and imperative language.
Scope
A scope is an object and it stores all the variables and their values.
Each time you create a new controller, Angular automatically create new scope object.
Each time you create a new controller, Angular automatically create new scope object.
Module
A module is a collection of directives, controllers and other stuff.
- Create a module
- var myModule = angular.module("myMod",[]);
- array contain list of other modules that the defined module depend upon
- Use the module
- <html ng-app="myMod">
- Register the module
- myMod.controller("myCtrl",main)
- myCtrl: controller name
- main: defined function for that controller
- Use the controller
- <ng-controller = "myCtrl">
Dependency Injection
Dependency injection is a software design pattern which enable components to fetch their dependencies instead of hardcoding them inside the component.
Angular Directives
- ng-app
- Use to indicate that this is an Angular application
- Indicate the root of the Angular application (added element is considered as the root element)
- ng-init
- Use to write initialization codes
- But actually, this is not the best way to write initialization codes
- ng-if
- Use to check conditions
- ng-bind
- bind the variable values into html elements
- one way binding method (data to view)
- shorthand : {{varaiblename}} = ng-bind="variablename"
- ng-controller
- Use to execute functions and initialization code
- ng-click
- Use to execute defined function when defined button click
- ng-model
- Use to fetch the data from the view and update the scope variables
- ng-hide/ ng-show
- Use to hide and show some html contents
- ng-repeat
- Use to iterate through loops.
- For each iteration, Angular automatically create new scope object
- Properties :
- $index: Return index no of the element
- $first: Return true if it's the first element
- $last: Return true if it's the last element
Services
Services are a reusable component that can use in multiple controllers.
- To share the same variable in different controllers
- ues value service
- ex : app.value("varName","varValue");
- Then access in controller function
- function myctrl(varName){this.variable = varName}
- To share constant values in different controllers
- use constant service
- ex : app.constant("constName","constVal")
- If you want to get the shared variable value from some complex logic
- use factory service
- app.factory("varName","function")
- If you want to use constructor functions as variable
- use service service
- app.service("varName","constructorFunction")
Promises
Promises is an alternative way to deal with asynchronous callback functions. Promise represent an operation that hasn't completed yet but is expected in the future.
GitHub Repository: https://github.com/kaosadi17/AngularJS
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