Undefined is not a function error in JavaScript

The “undefined is not a function” error in JavaScript is a common issue that can occur when working with objects and functions. This error occurs when you try to call a function that is not defined or when you try to call a property of an object that does not exist.

There are a few common causes of this error, including:

• Forgetting to include a required library or file
• Typing errors in the function or object name
• Using an object that is not yet fully loaded
• Attempting to call a function before it has been defined
• Here are a few examples of how this error can occur and how to fix it:

Example 1:

//undefined function call
let myFunction = undefined
myFunction()

Solution:

//define the function
let myFunction = function () {
  console.log("Hello World")
}
myFunction()

Example 2:

//undefined object property call
let myObject = {}
console.log(myObject.property)

solution

//define the object property
let myObject = { property: "Hello World" }
console.log(myObject.property)

Example 3:

//undefined object call
let myObject
console.log(myObject.property)

solution

//define the object
let myObject = { property: "Hello World" }
console.log(myObject.property)

In all cases, the issue is caused by undefined value, either the function, object or object property. To fix this error, you need to ensure that the function or object you are trying to call is properly defined and that any required libraries or files are included in your code.

Another important thing is to check the typo, make sure you are calling the function or property with the correct name, that way you can avoid the “undefined is not a function” error.

By following these tips, you should be able to fix the “undefined is not a function” error in your JavaScript code and get your application running smoothly again.