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JavaScript Closure

What is closure? It is my personal experience, I have never understood closure, I have read many articles & have seen many videos. Finally, I understood sometimes we even used a closure without realizing we were using a closure. First, understand the meaning of closure “an act or process of closing something”, now we can relate closure in javascript, closure is an inner function which wraps inside the outer function, which can access outer function scope & global function scope. for scoping you can read my previous blog:- http://uisource.blogspot.com/2018/08/javascript-variable-scoping.html why do we create? Global variables can be made local (private) with closures. To avoid the usage of global variables, use the local variables and wrap your code in the closure. A closure is an inner function that has access to the outer (enclosing) function’s variables—scope chain(Lexical scoping). The closure has three scope chains: it has access to its own scope (variables define
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JavaScript Variable Scoping

There are two types of variables in JavaScript.  Global variables have global access and are declared outside of any function. Local variables are those declared inside of function. Lexical Scoping(Nested JavaScript Function) means that in a nested group of functions, the inner functions have access to the variables and other resources of their parent scope. Global variable:- Global variable declares & initialize outside the function, & accessible in from anywhere in the code. The global variable always stored in memory even function execution finish, it always keeps in memory or always accessible from anywhere in the code. Example 1 var message= "hello i am global variable" ; //global variable function a (){ console.log(message); // output: hello i am global variable } function b (){ console.log(message); // output: hello i am global variable } function a() function b() In above example message is a global variable, it can be acces
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JavaScript type hoisting with variable function Expression

JavaScript type hoisting with variable function Expression Hoisting is JavaScript default behavior to moving declaration on the top. Variable can be used before its declaration. To understand this, first we need to understand of hoist meaning, hoist means “raise(something) by means of ropes & pulleys”. now we can relate hoisting with JavaScript. JavaScript interpreter moves all declaration on the top at runtime. It is best practice to declare all variable at the top of their respective scopes. , JavaScript is loosely syntax language so it will not throw any error at runtime if the variable used before its declaration. But JavaScript does not allow variable used before its declaration in “use strict” mode. Example 1 In this example, we can see in a normal scenario, when y has declared & then used. in this case, it will give output 10 as excepted. <p id= "demo" ></p> <script> var y; //Declare y y = 10 ;
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HTML Basic

HTML (Hypertext Markup Language) Basic What is HTML ? HTML invented by Tim Berners-Lee in 1990. HTML stands for hypertext markup language. Web browsers receive HTML documents from a web server or from local storage and render the documents into multimedia web pages .We can create web page with different elements like audio, video, image, tables, link, list & text etc, with CSS & JavaScript. version of HTML There are 6 version of HTML HTML Version Year HTML 1991 HTML 2.0 1995 HTML 3.2 1997 HTML 4.01 1999 XHTML 2000 HTML 5 2014 (Latest version) Latest version of HTML Latest version of html is HTML 5.0 , in latest version of html provided new tags for multimedia support. Now we are creating web page  index.html  How we can create Web page <!DOCTYPE html> < html > < head > < title > This is my First Web Page </ title > </ head > < body > < h1 > My First heading </ h1 &
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