This content originally appeared on DEV Community and was authored by Utkarsh Yadav
Table of content
- Shortest program in JavaScript
- window keyword
- This keyword
- Working behind the scenes
What is the shortest program in JavaScript ?
Running an empty file in JavaScript is the shortest program in JavaScript.
Create a JavaScript file with .js extension and compile the file using Dev Tools in the browser and the magic you would see that even though you have not written a piece of code but your JavaScript engine in the browser will create a complete new Global Execution context with all the methods and API available to you by your browser.
Isn't it interesting?.
Window Keyword
This is a functionality provided by JavaScript engine. basically window is the class in which various functions and methods are encapsulated.
These functions and methods can be used anywhere inside our JavaScript program.
This Keyword
This is an another functionality provided by JavaScript engine. At the Global level this points to window keyword and their functionality.
This is how JavaScript runs --> A global Context is created --> window object is created on initialised by the browser --> the this variable points to the window is created and the complete shortest program of JavaScript runs.
Working behind the scenes.
Steps are:
- Global Space creation: Anything not inside and block scope or a function scope is said to be in or bounded with Global Space.
Window keyword is Global Space.
So, everything outside the function will be under window keyword object or Global State Object.
Let's see an example to understand it better.
var a = 10; // Global space
function b() { // Global space
var x = 10; // Not in Global space
}
console.log(window.a); // Global space
console.log(a); // Global space
console.log(x); // Global space
Points to be noted:
- Everything that is inside Global Space are accessed inside
windowobject. - Everything that is outside Global Space are not accessed inside
windowobject.
Conclusion: This vs window points to the same global space.
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Happy Coding!
This content originally appeared on DEV Community and was authored by Utkarsh Yadav
Utkarsh Yadav | Sciencx (2021-06-17T15:04:42+00:00) Window and this keyword, what the heck it is?. Retrieved from https://www.scien.cx/2021/06/17/window-and-this-keyword-what-the-heck-it-is/
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