Types of JavaScript Functions

  • By Sonal Vanarse
  • March 2, 2024
  • JavaScript
Types of JavaScript Functions

Types of JavaScript Functions

JavaScript functions come in different types and have various differences, especially in ES6 (ECMAScript 2015) and later versions. Here’s a breakdown types of JavaScript functions and some ES6 features related to functions:

Function Types:

  • Named Functions:

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function add(a, b) { return a + b; } 

  • Anonymous Functions:

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const add = function(a, b) { return a + b; }; 

  • Arrow Functions (Introduced in ES6):

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const add = (a, b) => a + b; 


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Differences and Features:

  • Arrow Functions:

      • Concise syntax: Arrow functions provide a shorter syntax compared to traditional function expressions.
      • Lexical this: Arrow functions do not have their own this value. Instead, this is lexically bound, meaning it’s inherited from the enclosing scope.
      • Cannot be constructors: Arrow functions cannot be used as constructors with the new keyword.
      • No arguments binding: Arrow functions do not have their own arguments object. Instead, they inherit it from the enclosing scope.
  • Function Scoping:

      • ES6 introduced let and const which have block scope, unlike var which has function scope. This affects how functions declared with these keywords are scoped.
  • Default Parameters (Introduced in ES6):

    • You can set default values for parameters directly in the function signature.

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function greet(name = ‘World’) { console.log(`Hello, ${name}!`); } greet(); // Output: Hello, World! greet(‘John’); // Output: Hello, John! 

  • Rest Parameters (Introduced in ES6):

    • Rest parameters allow a function to accept an indefinite number of arguments as an array.

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function sum(…numbers) { return numbers.reduce((acc, curr) => acc + curr, 0); } console.log(sum(1, 2, 3, 4)); // Output: 10 

  • Spread Syntax (Introduced in ES6):

    • The spread syntax allows an iterable such as an array expression or string to be expanded in places where zero or more arguments or elements are expected.

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const arr1 = [1, 2, 3]; const arr2 = [4, 5, 6]; const combinedArray = […arr1, …arr2]; // Output: [1, 2, 3, 4, 5, 6] 

  • Template Literals (Introduced in ES6):

    • Template literals provide an easy way to interpolate variables into strings using ${} syntax.

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const name = ‘John’; console.log(`Hello, ${name}!`); // Output: Hello, John! 

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These features introduced in ES6 enhance the capabilities and expressiveness of Advanced JavaScript functions, making them more concise and powerful.


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