JavaScript indexOf() method in an Object Array Last Updated : 14 Mar, 2024 Comments Improve Suggest changes Like Article Like Report In JavaScript, indexOf() methods provide the first index at which the given element exists, and -1 in case it is not present in the array. Syntax: indexOf(element)indexOf(element, start);Parameters: element: the element to be searched in the input arraystart: the index from which the search has to begin. The default value is set to 0.Return value: JavaScript indexOf() method returns the value of the index at which the element is present, and -1 when the element doesn't exist. JavaScript indexOf() method in an Object Array ExamplesExample 1: Basic Usage In this example, the indexOf() method returns -1 because the object { name: 'banana', color: 'yellow' } is a different object instance than the one stored in the array. JavaScript let fruits = [ { name: 'apple', color: 'red' }, { name: 'banana', color: 'yellow' }, { name: 'orange', color: 'orange' } ]; // Find the index of an object in the array let index = fruits.indexOf({ name: 'banana', color: 'yellow' }); console.log(index); // Output: -1 (Not found) Output-1 Example 2: Index of Modified Object In this case, the modified banana object is added to the array, and then indexOf() method returns the index where this modified object is located. JavaScript // Example Title: Finding Index of a Modified Object // Array of objects representing fruits let fruits = [ { name: 'apple', color: 'red' }, { name: 'banana', color: 'yellow' }, { name: 'orange', color: 'orange' } ]; let banana = { name: 'banana', color: 'yellow' }; // Finding the index of an object after modifying it fruits.push(banana); // Adding the modified object to the array let index = fruits.indexOf(banana); console.log(index); // Output: 3 Output3 Comment More info P PranchalKatiyar Follow Improve Article Tags : JavaScript Web Technologies javascript-array javascript-object JavaScript-Questions +1 More 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)9 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