Day 27: Debugging

Whether you're a beginner or a seasoned developer, understanding how to leverage Chrome DevTools for debugging, handling memory leaks, and optimizing performance can significantly enhance your development process.

1. Debugging JavaScript

Debugging is an essential skill for every developer. Chrome DevTools provides a robust set of tools that can make the debugging process much more efficient.

• 🔍 Using the Console: The Console panel within DevTools allows you to log, inspect, and interact with JavaScript code running on your page. You can use console.log() statements to print values, objects, and debug information directly to the console.
• 🐞 Setting Breakpoints: Breakpoints let you pause the execution of your code at specific lines, allowing you to inspect variables and the call stack at that point. You can set breakpoints by clicking on the line number in the Sources panel or by using the debugger; statement in your code.
• 🔗 Utilizing the Debugger: The debugger statement triggers the built-in JavaScript debugger, pausing code execution. This is particularly helpful when you need to dive into the flow of execution and analyze variables.

function calculateTotal(price, tax) {
    debugger;
    const total = price + (price * tax);
    return total;
}
const totalPrice = calculateTotal(100, 0.2);
console.log(totalPrice);

2. Debugging Memory Leaks

Memory leaks can lead to performance issues in your applications. Chrome DevTools provides tools to help identify and rectify memory leaks.

🔍 Memory Panel:
The Memory panel enables you to take snapshots of the heap and compare memory usage over time. This helps identify objects that are not being garbage collected as expected.

🔄 Heap Snapshots:
You can take heap snapshots and analyze them to find memory-consuming objects that should ideally be released. DevTools even highlights objects that are causing memory leaks.

function createLeak() {
    const element = document.getElementById('leakyButton');
    element.addEventListener('click', function() {
        // Some action
    });
}

check out official chrome developer doc for more info

3. Debugging Performance

Optimizing your JavaScript code for better performance is crucial. DevTools offers tools to analyze performance bottlenecks and enhance the speed of your applications.

⏱️ Performance Panel:
The Performance panel helps you record and analyze the execution timeline of your application. It identifies issues like long tasks, layout recalculations, and more.

📊 Flame Charts:
Flame charts visually represent the time spent on different tasks during a certain time period. This aids in pinpointing exactly where your code might be causing performance slowdowns.

Suppose you have a page with a slow rendering issue due to excessive layout calculations:

function calculateLayout() {
    // Complex layout calculation
}
// Trigger layout calculation on button click
document.getElementById('layoutButton').addEventListener('click', calculateLayout);

check out official chrome developer doc for more info