Debugging in Node JS

Hello everyone. My name is Julian and today we will understand how we can debug our code in Node JS. For understanding it better
Let’s go with a story about a bakery that recently opened and is gaining popularity.
However, the head baker, Ishita, has noticed that not everything is running smoothly.
Each day, there’s an unexpected issue with orders, recipes, or equipment, causing delays and unhappy customers.
Ishita realizes she has to investigate each problem type carefully to keep her bakery running smoothly.

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Types of “Errors” in Ishita’s Bakery

1. Recipe Mistakes (Syntax Errors):
   • One day, Ishita notices the brownies are coming out too hard. After checking, she realizes the recipe card has a typo that says “1 cup flour” instead of “½ cup flour.”
   • This is similar to a syntax error in programming, where a small mistake in code structure, like a missing bracket or incorrect keyword, can throw off the whole program.
     
2. Missing Ingredients (Runtime Errors):
   • On another day, Ishita starts making a batch of cookies but realizes halfway through that they’ve run out of chocolate chips.
   • This is like a runtime error in programming, where an error arises while the program is running, often due to missing data or variables that aren’t available when expected.
     
3. Flavor Issues (Logical Errors):
   • Ishita follows a recipe but keeps getting complaints that the muffins taste bitter. She reviews her steps and finds she’s been adding baking soda twice, once at the beginning and again by mistake.
   • This is similar to a logical error in code, where the program runs but produces the wrong results because of flawed logic or incorrect calculations.
     
4. Ingredient Mix-up (Type Errors):
   • Another day, Ishita accidentally grabs salt instead of sugar for a batch of cupcakes. The cupcakes bake fine, but they taste terrible.
   • This reflects a type error in programming, where an operation fails because the wrong data type is used—like trying to add a string to a number.
     
5. Oven Problems (System Errors):
   • One morning, the bakery’s oven won’t heat up properly, and everything is baking slower than expected, throwing off the whole day’s schedule.
   • This is like a system error in programming, where external issues like file permissions, network problems, or system limitations interfere with the program’s ability to run smoothly.

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Why is Debugging Important in Ishita’s Bakery?

Just like Ishita needs to find and fix each type of error to keep her bakery running efficiently, debugging in programming is essential for identifying and resolving issues that disrupt code functionality. Each type of error requires careful attention to ensure everything “bakes” just right!

Now that we understand the types of errors, we can explore specific debugging techniques in Node.js. Should we start with simple techniques like console.log to catch errors?

NodeJS implementaion:

Task Breakdown

1. Example of Form Submission with Logical Error
   • Let’s look at a form submission example where a logical error is causing the wrong message to be written into a text file. The code might seem correct at first glance, but when we test it, the output doesn’t match our expectations.
     
     
     
2. Using Breakpoints and Step Over
   • To trace the root cause of this error, we’ll set breakpoints at specific points in the code. Breakpoints pause the execution, allowing us to examine the program state at that moment.
   • By using the “Step Over” feature, we can move through each function call one step at a time, checking the flow and data to pinpoint where the error is occurring. This process helps us see if any logic is misdirected or if values aren’t updating as expected.
   • -Show Error in split function 
3. Modifying Values During Debugging
   • A powerful feature in the debugger is the ability to change variable values on the spot.
     By adjusting values directly in the debugger, we can see how different inputs impact the program’s behavior, helping us confirm and correct issues without restarting the program.

Conclusion

• Debugging is essential for fixing issues in code, similar to how Ishita resolves problems in her bakery.
• In Node.js, we used:
  • Breakpoints to pause and inspect code in real-time.
  • Step Over to trace the function flow step-by-step.
  • Modifying values mid-debug to test and confirm fixes instantly.
• These techniques help us catch and correct errors efficiently, ensuring our programs function smoothly.