Something happened! 🤔 TypeError: Cannot read properties of undefined (reading 'split') ✅ executes this line, as data has undefined valueĬonsole.log('Something happened! 🤔', error) ❌ Fails this condition, as data is a undefined If data has undefined, then an empty string is stored in the variable data. Let str = data || '' // fallback empty string if falsy

Fallback ( ❌ Not recommended ) let data = undefined will call the split() method if the data variable is not equal to undefined or null otherwise, it will return undefined, and no error is thrown. } Optional chaining ( ✅ Recommended ) let data = undefined Ĭonsole.log(data?.split('')) // prints undefined We can use undefined and the strict equality to determine whether a variable has a value. Alternatively, typeof can also be used to determine whether a variable is of undefined type. The following check will let us know if the variable we are dealing with is a string or any other type.ī). We need to call the split method only on strings.

There are quite a few ways to solve this errorĪ).

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The following courses help you learn true basics and advanced Javascript concepts. We will also see similar split errors with null object, APIs etc. In this article, you will learn how these errors appear on the application and different methods to solve them. In both of the above snippets, we cannot call split() method on a variable that has an undefined value. When we declare a variable without assigning any value.

When we assign undefined to a variable.Ĭonsole.log(data.split(',') // Uncaught TypeError: Cannot read properties of undefined (reading 'split')Ģ.

How to replicate this error?įollowing are the two ways how JavaScript engine treats a variable as undefined. In simple words, when we do not assign any value to a variable, the JavaScript engine treats it as `undefined`. In JavaScript, a variable is said to be undefined if it has been declared but not initialized. The ' cannot read property split of undefined' error occurs when we try to call the split() method on a variable that stores an undefined value.

Javascript is undefined