Introduction
In this lab, we will explore the concept of value in JavaScript and how to check if a specified value is undefined. This lab will give you hands-on experience in writing code to determine the presence of undefined values using the strict equality operator. By the end of this lab, you will have a solid understanding of how to use the isUndefined() function to check for undefined values in your JavaScript programs.
This is a Guided Lab, which provides step-by-step instructions to help you learn and practice. Follow the instructions carefully to complete each step and gain hands-on experience. Historical data shows that this is a beginner level lab with a 100% completion rate. It has received a 97% positive review rate from learners.
Checking for Undefined Value
To check if a value is undefined, open the Terminal/SSH and type node.
- Use the strict equality operator to check if
valis equal toundefined.
const isUndefined = (val) => val === undefined;
isUndefined(undefined); // true
This code will check if the specified value is undefined.
Summary
Congratulations! You have completed the Value Is Undefined lab. You can practice more labs in LabEx to improve your skills.