JavaScript TypeError - Can't access property "X" of "Y" Last Updated : 02 Jun, 2023 Comments Improve Suggest changes Like Article Like Report This JavaScript exception can't access property occurs if property access was performed on undefined or null values. Message: TypeError: Unable to get property {x} of undefined or null reference (Edge) TypeError: can't access property {x} of {y} (Firefox) TypeError: {y} is undefined, can't access property {x} of it (Firefox) TypeError: {y} is null, can't access property {x} of it (Firefox) Examples: TypeError: x is undefined, can't access property "prop" of it TypeError: x is null, can't access property "prop" of it TypeError: can't access property "prop" of undefined TypeError: can't access property "prop" of null Error Type: TypeError Cause of Error: The property access was performed on any of the undefined or null values in the code. Example 1: In this example, the GFG is undefined, So the error has occurred. HTML let GFG = undefined; GFG.substring(3); // error here Output(in console): TypeError: Unable to get property 'substring' of undefined or null reference Example 2: In this example, the GFG is null, So the error has occurred. JavaScript let GFG = null; GFG.substring(3); // error here Output(in console): TypeError: Unable to get property 'substring' of undefined or null reference Comment More infoAdvertise with us P PranchalKatiyar Follow Improve Article Tags : JavaScript Web Technologies JavaScript-Errors Explore JavaScript Tutorial 8 min read JavaScript BasicsIntroduction to JavaScript 4 min read JavaScript Versions 2 min read How to Add JavaScript in HTML Document? 3 min read JavaScript Syntax 6 min read JavaScript Output 4 min read JavaScript Comments 2 min read JS Variables & DatatypesVariables and Datatypes in JavaScript 6 min read Global and Local variables in JavaScript 4 min read JavaScript Let 6 min read JavaScript const 5 min read JavaScript Var Statement 7 min read JS OperatorsJavaScript Operators 5 min read Operator precedence in JavaScript 2 min read JavaScript Arithmetic Operators 5 min read JavaScript Assignment Operators 5 min read JavaScript Comparison Operators 5 min read JavaScript Logical Operators 5 min read JavaScript Bitwise Operators 5 min read JavaScript Ternary Operator 4 min read JavaScript Comma Operator 2 min read JavaScript Unary Operators 4 min read JavaScript in and instanceof operators 3 min read JavaScript String Operators 3 min read JS StatementsJavaScript Statements 4 min read JavaScript if-else 3 min read JavaScript switch Statement 4 min read JavaScript Break Statement 2 min read JavaScript Continue Statement 1 min read JavaScript Return Statement 4 min read JS LoopsJavaScript Loops 3 min read JavaScript For Loop 4 min read JavaScript While Loop 3 min read JavaScript For In Loop 3 min read JavaScript for...of Loop 3 min read JavaScript do...while Loop 4 min read JS Perfomance & DebuggingJavaScript | Performance 4 min read Debugging in JavaScript 4 min read JavaScript Errors Throw and Try to Catch 2 min read JS ObjectObjects in Javascript 4 min read Object Oriented Programming in JavaScript 3 min read JavaScript Objects 6 min read Creating objects in JavaScript 5 min read JavaScript JSON Objects 3 min read JavaScript Object Reference 4 min read JS FunctionFunctions in JavaScript 4 min read How to write a function in JavaScript ? 4 min read JavaScript Function Call 2 min read Different ways of writing functions in JavaScript 3 min read Difference between Methods and Functions in JavaScript 3 min read Explain the Different Function States in JavaScript 3 min read JavaScript Function Complete Reference 3 min read JS ArrayJavaScript Arrays 7 min read JavaScript Array Methods 7 min read Best-Known JavaScript Array Methods 6 min read Important Array Methods of JavaScript 7 min read JavaScript Array Reference 4 min read Like