Create Function Expressions In JavaScript

In JavaScript, a function declaration defines a function with the specified parameters and code block.

Functions can be called before their creation due to hoisting. A JavaScript function is a subprogram that can be called by code externally or internally to the function. Function expressions are a way to assign to variables such as passing as arguments or invoking.

Function expressions are defined using the function keyword following by parentheses containing optional arguments.

Common Syntax Of Function Expressions In JavaScript

Glossary:

Hoisting

The interpreter moves function declaration to the top of their scope.

Scope

The accessibility of variables and functions within certain parts of your code.

Declaration

Used to define variables, functions, and constants.

Method

Function defined within a object.

Named Expression

Accessed by name only within the function.

Anonymous Expression

Do not have name and typically assigned to a variable.

Immediately Invoked Function Expression

(IIFE) called immediately after it is defined.

Arrow Functions

Syntax for creating anonymous expressions.

Common Function Expressions

Ojamboshop.com Learning JavaScript Function Expressions

Name	Description	Example
function()	Anonymous function expression.	let n = function() {};
function myFunc()	Named function expression.	let m = function myFunc() {};
(function())()	Immediately Invoked Function Expression.	(function() {})();
() => {}	Arrow function anonymous expression.	let a = () => {};
Name	Description	Example

JavaScript Function Expressions Snippet

// OjamboShop.com Learning JavaScript Function Expressions Tutorial

// Anonymous Function Expression
let anonymous = function() {
	console.log('called anonmymous function');
}
anonymous;

// Named Function Expression
let named = function displayName(name) {
	console.log('The name is ' +name);
};
named('John');

// IIFE
(function() {console.log('IIFE');})();

// Arrow Function
let calculateSum = (num1, num2) => {return (num1 + num2);};
console.log('The sum of 2 numbers is ' + calculateSum(5,3));

Usage

You can use any IDE or text editor and the web browser to compile and execute JavaScript code. For this tutorial, the OjamboShop.com Learning JavaScript Course Web IDE can used to input and compile JavaScript code for the function expressions.

Open Source

JavaScript follows the ECMAScript standard and is licensed under the W3C Software License by web browser vendors and runtime environment vendors. This allows commercial use, modification, distribution, and allows making derivatives proprietary.

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Conclusion:

JavaScript makes it easy to use create function expressions. Define functions as part of an expression for assigning to variables, arguments, or invoking immediately.

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