Underscore.js _.uniqueId() Function Last Updated : 15 Oct, 2020 Comments Improve Suggest changes Like Article Like Report Underscore.js is a JavaScript library that provides a lot of useful functions that help in the programming in a big way like the map, filter, invoke, etc even without using any built-in objects. The _.uniqueId() function is an inbuilt function in Underscore.js library of JavaScript which is used to generate a globally unique id for the client-side models or the DOM elements which requires one. When a prefix is passed as an argument to this method, the id generated will be appended to it. Syntax: _.uniqueId( prefix ) Parameters: It accepts a single parameter as mentioned above and described below: prefix: It is the prefix that would be appended to the id It is am optional parameter. Return Value: This method returns a globally unique id. Example 1: HTML <!DOCTYPE html> <html> <head> <script src= "https://unpkg.com/[email protected]/underscore-min.js"> </script> </head> <body> <script type="text/javascript"> // Using _.uniqueId() method // with its parameter console.log(_.uniqueId('gfG_')); console.log(_.uniqueId('Geeks_')); console.log(_.uniqueId('CS_')); </script> </body> </html> Output: gfG_1 Geeks_2 CS_3 Example 2: HTML <!DOCTYPE html> <html> <head> <script src= "https://unpkg.com/[email protected]/underscore-min.js"> </script> </head> <body> <script type="text/javascript"> // Using a loop for (i = 3; i < 100; i *= 2) { // Calling uniqueId method // without any parameter console.log(_.uniqueId()); } </script> </body> </html> Output: 1 2 3 4 5 6 Create Quiz Comment N nidhi1352singh Follow 0 Improve N nidhi1352singh Follow 0 Improve Article Tags : JavaScript Web Technologies JavaScript - Underscore.js 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