Скачать или смотреть Understanding Why Your if Statement Isn't Working in JavaScript

Are you a newbie in JavaScript facing issues with your `if` statements? This post explains the common pitfalls and provides a simple solution to help you get it right.
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This video is based on the question https://stackoverflow.com/q/75150812/ asked by the user 'kado-kliewer23' ( https://stackoverflow.com/u/21029944/ ) and on the answer https://stackoverflow.com/a/75150860/ provided by the user 'Rohit Khanna' ( https://stackoverflow.com/u/7306148/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Why Your if Statement Isn't Working in JavaScript: A Beginner's Guide

As a newcomer to coding, diving into JavaScript can be both exciting and challenging. Many beginners encounter issues when trying to understand how objects and functions interact. One common problem is using conditional statements incorrectly, which can lead to unexpected results. This guide will explore a specific coding challenge you might face: why an if statement regarding object properties is not yielding the correct outcome.

The Problem at Hand

You have a piece of code that checks certain properties of a user object to determine whether to grant access or not. Here's the relevant function:

[[See Video to Reveal this Text or Code Snippet]]

When you run this code, it always logs: "Please get a parent's permission before playing this game." Let's break down why that happens.

Analyzing the Conditional Statement

In the if statement, you have this condition:

[[See Video to Reveal this Text or Code Snippet]]

What This Condition Means

user.fName === true: This checks if the property fName of the user object equals true.

user.lName === true: Similarly, it checks if the property lName equals true.

user.age >= 18: This checks if the user is 18 years old or older.

Why It Fails

Here’s the crux of the issue: Both fName and lName are string values (e.g., "Kado" and "Kliewer"). When you check if a string equals true, it will return false because a string does not inherently evaluate to boolean true.

Put simply:

user.fName evaluates to "Kado" (a string).

Since the condition user.fName === true evaluates to false, the entire if statement fails.

The Solution: Correcting the Conditional Logic

To make your code work as intended, the condition should check whether fName and lName exist (are defined and not empty), rather than checking if they equal true. Here’s how you can adjust the if condition:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Solution

user.fName && user.lName: This checks if both fName and lName are truthy values (not null, undefined, 0, '').

user.age >= 18: This remains unchanged as it correctly checks for the age.

With this logic, if the object user has valid fName and lName properties, and the age is 18 or older, the welcome message will be logged correctly.

Conclusion

Understanding how to check object properties in JavaScript is crucial for beginners. The error you faced was a common pitfall transitioning from beginner to intermediate understanding of JavaScript. By making sure you’re checking the properties correctly, you can unlock many functionalities in your code. Now, try running the adjusted code and enjoy the positive greeting!

If you find yourself stuck again, remember that breaking down conditions and understanding types can always help clarify the confusion. Happy coding!