Functions in JavaScript are one of the core building blocks of modern web development. They allow us to encapsulate reusable code and execute it as needed. Understanding functions is key to mastering JavaScript.
A function in JavaScript is defined using the function keyword, followed by a name, a list of parameters inside parentheses, and a block of code inside curly braces.
function greet ( ) {
console .log ("Hello, World!" );
}
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To execute a function, you simply call it by its name followed by parentheses.
Functions can take parameters, which are used as variables inside the function.
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In ES6, JavaScript allows default parameter values in functions.
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A function can return a value back to the caller using the return
statement.
function sum (a, b ) {
return a + b;
}
let result = sum (5 , 3 );
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Functions in JavaScript can be defined without a name – these are called anonymous functions.
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Function expressions allow us to create a new function inside an expression.
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ES6 introduced arrow functions , which provide a concise way to write functions in JavaScript.
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Arrow functions do not have their own this
context, which makes them ideal for certain scenarios.
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Mastering JavaScript functions is a fundamental step in becoming a proficient JavaScript developer. From simple function definitions to complex ES6 arrow functions, understanding these concepts will enhance your ability to write efficient and clean code.