JavaScript Function Examples Last Updated : 01 Dec, 2025 Comments Improve Suggest changes 3 Likes Like Report JavaScript functions are reusable blocks of code designed to perform a specific task. They help organize your program, reduce repetition, and make your code easier to read and maintain.A function is defined using the function keyword or arrow (=>) syntax.Functions accept parameters as input and return results using return.Functions run only when they are called (invoked) in your code.JavaScript Function ExamplesThe following JavaScript section contains a wide collection of JavaScript examples. Many of these programming examples contain multiple approaches to solve the problem.Write a function Currying functionCalling a JavaScript function in HTMLsetTimeout() functionAnonymous functionsCheck whether a number is NaN or finite Encode and decode a URLDeclare the optional function parametersDynamic JavaScript function parameters.Importing one JavaScript file into anotherOverriding a JavaScript functionUsing function declarationDifference between call and applyCaller function Negating a predicate functionIterate over a callback n timesCall a function with preset argumentsRemoving specific keys from an objectCalling multiple functions with the same arguments Calling a function by its name as a stringMeasure time taken by a function to executeCheck a function is definedCall a function with modified arguments Wait for a promise before returning a valueChange a global variable inside a functionGetting the index of the fastest function in an arrayAdd an element horizontally in Html page Adding fade-out effect Add fade-in effect Understanding setTimeout() code snippetsFor More details follow these articles : JavaScript Function Complete ReferenceJavaScript ExamplesJavaScript Tutorial Create Quiz Comment V vishalkumar2204 Follow 3 Improve V vishalkumar2204 Follow 3 Improve Article Tags : JavaScript Web Technologies Explore JavaScript BasicsIntroduction to JavaScript4 min readVariables and Datatypes in JavaScript6 min readJavaScript Operators5 min readControl Statements in JavaScript4 min readArray & StringJavaScript Arrays7 min readJavaScript Array Methods7 min readJavaScript Strings5 min readJavaScript String Methods9 min readFunction & ObjectFunctions in JavaScript5 min readJavaScript Function Expression3 min readFunction Overloading in JavaScript4 min readObjects in JavaScript4 min readJavaScript Object Constructors4 min readOOPObject Oriented Programming in JavaScript3 min readClasses and Objects in JavaScript4 min readWhat Are Access Modifiers In JavaScript ?5 min readJavaScript Constructor Method7 min readAsynchronous JavaScriptAsynchronous JavaScript2 min readJavaScript Callbacks4 min readJavaScript Promise4 min readEvent Loop in JavaScript4 min readAsync and Await in JavaScript2 min readException HandlingJavascript Error and Exceptional Handling6 min readJavaScript Errors Throw and Try to Catch2 min readHow to create custom errors in JavaScript ?2 min readJavaScript TypeError - Invalid Array.prototype.sort argument1 min readDOMHTML DOM (Document Object Model)8 min readHow to select DOM Elements in JavaScript ?3 min readJavaScript Custom Events4 min readJavaScript addEventListener() with Examples9 min readAdvanced TopicsClosure in JavaScript4 min readJavaScript Hoisting6 min readScope of Variables in JavaScript3 min readJavaScript Higher Order Functions7 min readDebugging in JavaScript4 min read Like