Use Optional Chaining
For more complex scenarios use optional chaining to the safely access nested properties.
let person = undefined;
person?.address?.city = "New York"; // This will not throw an error
Example: Here is a complete example demonstrating how to fix the error using the various approaches.
// Initializing the object
let person = {};
person.name = "John Doe";
console.log(person); // { name: 'John Doe' }
// Checking for undefined
let car;
if (car === undefined) {
car = {};
}
car.model = "Tesla Model S";
console.log(car); // { model: 'Tesla Model S' }
// Using default parameters
function setAge(person = {}) {
person.age = 30;
return person;
}
let user = setAge();
console.log(user); // { age: 30 }
// Using optional chaining
let book;
book?.details?.title = "JavaScript Guide";
// Does not throw error
Time Complexity: The time complexity for these checks and initializations is generally O(1) since they involve the straightforward assignments and conditional checks.
Auxiliary Space: The auxiliary space required is minimal typically O(1) as it involves only a few additional variables for the checks and initializations.
How to Fix JavaScript TypeError: Cannot Set Properties of Undefined?
JavaScript is a versatile and widely used programming language but like any language, it can sometimes produce errors that can be tricky to debug. One common error that developers is the TypeError: Cannot set properties of the undefined. This error typically occurs when we attempt to assign a value to the property of an undefined object. In this article, we will explore the causes of this error how to identify it, and the steps taken to fix it.