JavaScript TypeError - X.prototype.y called on incompatible type Last Updated : 15 Jul, 2025 Comments Improve Suggest changes 1 Likes Like Report This JavaScript exception called on incompatible target (or object)" occurs if a function (on a given object), is called with a 'this' corresponding to a different type other than the type expected by the function. Message: TypeError: 'this' is not a Set object (EdgE) TypeError: Function.prototype.toString called on incompatible object (Firefox) TypeError: Function.prototype.bind called on incompatible target (Firefox) TypeError: Method Set.prototype.add called on incompatible receiver undefined (Chrome) TypeError: Bind must be called on a function (Chrome) Error Type: TypeError Cause of Error: Somewhere in function calls, a function (on a given object), is called with a 'this' not corresponding to the type expected by the function. Example 1: In this example, the GFG_Set.add is a function, but GFG_Set is not captured as 'this'. JavaScript let GFG_Set = new Set; ['Geek', 'GFG'].forEach(GFG_Set.add); Output(in console): TypeError: 'this' is not a Set object Example 2: In this example, GFG_Fun.bind is a function, but GFG_Fun is not captured as 'this'. JavaScript let GFG_Fun = function () { console.log(this); }; ['Geek', 'GFG'].forEach(GFG_Fun.bind); Output(in console): TypeError: 'this' is not a Set object Create Quiz Comment P PranchalKatiyar Follow 1 Improve P PranchalKatiyar Follow 1 Improve Article Tags : JavaScript Web Technologies JavaScript-Errors 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