JSON Modify an Array Value of a JSON Object Last Updated : 11 Jul, 2025 Comments Improve Suggest changes Like Article Like Report The arrays in JSON (JavaScript Object Notation) are similar to arrays in JavaScript. Arrays in JSON can have values of the following types: nullbooleannumberstringarrayobject The arrays in JavaScript can have all these but it can also have other valid JavaScript expressions which are not allowed in JSON. The array value of a JSON object can be modified. It can be simply done by modifying the value present at a given index. Example: Modifying the value present at an index in the array JavaScript let myObj, i; myObj = { // Stored the values "words": ["I", "am", "Good"] }; // Modifying the value present at index 2 myObj.words[2] = "bad"; for (i in myObj.words) { // Displaying the modified content console.log(myObj.words[i]); } OutputI am bad Note: If the value is modified at an index that is out of the array size, then the new modification will not replace anything in the original information but rather will be an add-on. Example: Modifying the value of the index which is out of the array size. JavaScript let myObj, i; myObj = { // Stored the values "words": ["I", "am", "Good"] }; // Modifying the value present at index 2 myObj.words[3] = "bad"; for (i in myObj.words) { // Displaying the modified content console.log(myObj.words[i]); } OutputI am Good bad Create Quiz Comment GeeksforGeeks 0 Improve GeeksforGeeks 0 Improve Article Tags : JavaScript 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