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Learn Javascript Functions
Introduction
This article explains JavaScript function in detail and followed the previous JavaScript article Learn JavaScript__Part1. Therefore if you are not familiar with JS basics, you may check the mentioned articles.
What are Functions in JavaScript?
Functions are containers that hold reusable code and perform a particular task. Not just JavaScript but almost all programming languages have a concept of functions and every developer must deal with that while coding.
Functions are independent pieces of code and manage the large code. Before moving on how it performs a task, let's see how we can create a function.
In javaScript the function keyword is used to declare a function, to identify a function it should have a name.
Here is the syntax for function declaration
function name(){YOUR_CODE}
Here is the example, the function "sayHi" can be created using a function keyword followed by "sayHi" [function name] and a set of parentheses, the function code will be written inside the curly braces. Whenever the function is called, it performs whatever instruction is written inside it, here I created this function that whenever it is called it should print I like JavaScript.
function sayHi(){ console.log("I like JavaScript") } sayHi();// I like JavaScript
Here is another function example
function myFunction(){ console.log("Hello world"); let c = 3 + 5; console.log(c); } myFunction();/* Hello world 8*/
JavaScript functions can be used as reusable code. In below example, I don't need to type the code every time I need it, I can just call the function.
function myFunction(){ console.log("Hello world"); let c = 3 + 5; console.log(c); } myFunction(); myFunction();/* Hello world 8 Hello world 8*/
Functions also accept parameters - parameters are the symbolic name for "data" that goes into a function. A function can have one or more parameters.
In the below example, the function has a parameter called num, num accepts a value and performs the function task based on that value. The parameter value will be initialized while calling the function.
function myFunction(num){ console.log(num * num) } myFunction(3); myFunction(10);/* 9 100*/
You don't need to console.log in functions, the " return " is used to return the function statements.
function myFunction(a, b){ return a + b; } console.log(myFunction(3, 5));// 8
Conclusion
That is it for this article. I hope you found this article useful, if you need any help please let me know in the comment section.
Feel free to contact me on Twitter
Original Link: https://dev.to/zahab/learn-javascript-functions-2f2g
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