Day / Days of Code: Advanced JavaScript Syntax

Mon, August 26, 2024

Hey everyone!

Today, I delved into some advanced JavaScript syntax while tackling CodeSignal challenges. One particular challenge focused on displaying time in both 24-hour and 12-hour formats. The goal was to sum the numerals in the time display—a task that might seem impractical but is designed to push the boundaries of problem-solving.

During this challenge, I encountered an interesting piece of code and sought clarification from Perplexity AI about the OR piping used in the following line:
let hours = (Math.floor(n / 60) % 12) || 12;

At first glance, this might be easy to overlook, but it’s a clever use of the logical OR operator in an assignment operation. According to Perplexity AI, this technique is known as the “logical OR trick” or “default operator”:

In JavaScript, the logical OR operator (||) doesn’t just return true or false. It returns the first “truthy” value it encounters. In JavaScript, 0 is considered a “falsy” value, while any non-zero number is “truthy”. The || operator first evaluates the expression on its left. If that expression is truthy, it returns that value. If it’s falsy, it moves on to evaluate and return the expression on its right.

This allows us to replace 0 with 12 concisely, without needing an if-statement. It’s particularly useful in this 12-hour clock scenario where we want 0 to become 12, but all other values to remain as they are.

Today’s challenge not only tested my problem-solving skills but also expanded my understanding of JavaScript’s logical operators. It’s fascinating how such small nuances can make a big difference in coding efficiency and readability. Does anyone have any favorite operators or next level syntax they'd like to share?

The above is the detailed content of Day / Days of Code: Advanced JavaScript Syntax. For more information, please follow other related articles on the PHP Chinese website!