Ask Programiz - Human Support for Coding Beginners

Hello Anna, really nice question.

*= is just a shortcut for multiplying a variable by something and then storing the new value back into that same variable. It follows the same pattern as +=, which adds to the existing value.

So instead of writing:

x = x * 5

you can write:

x *= 5

Both do exactly the same thing — the second one is just shorter and easier to read once you get used to it.

If you have further questions, I'm here to help.

Hello agegnw, really nice question.

In JavaScript, slice() is used to take a part of a string and return it as a new string, without changing the original one.

It works with indexes (positions of characters in the string). JavaScript starts counting from 0.

Basic form:

string.slice(startIndex, endIndex)

• startIndex → where to start (included)

• endIndex → where to stop (excluded). If you leave this out, it goes to the end of the string.

Example:

let text = "JavaScript is fun!";

let part1 = text.slice(0, 10);   // from index 0 to 9
console.log(part1);              // "JavaScript"

let part2 = text.slice(11);      // from index 11 to the end
console.log(part2);              // "is fun!"

In the kind of example from your lesson, you might see something like:

let name = "  alice  ";
let trimmed = name.trim();       // "alice"
let result = trimmed[0].toUpperCase() + trimmed.slice(1);
console.log(result);             // "Alice"

Here:

• trim() removes spaces at the start and end.

• slice(1) takes the string from index 1 onward ("lice"), so you can rebuild "Alice".

So you can think of it this way:

• trim() → cleans spaces from the ends.

• slice() → cuts out the piece of the string you want.

If you have further questions, I'm here to help.

Hello James, really nice question.

In JavaScript, the easiest way to make the output look cleaner with a dollar sign is to format it as a string. A very common way to do that is with a template literal (using backticks `):

let costPrice = 25;
let sellPrice = 35;

let profit = sellPrice - costPrice;

console.log(`Profit: $${profit}`);

What’s happening here:

• The backticks let you write a string with embedded expressions.

• ${profit} is replaced by the actual value of profit.

• The $ before it is just a normal character in the string, so it shows up exactly as you’d expect.

You could also do it with string concatenation:

console.log("Profit: $" + profit);

Both work, but template literals are usually cleaner and easier to read, especially as the text gets longer.

If you have further questions, I'm here to help.

Template literals are another way to write strings in JavaScript using backticks instead of quotes. The helpful thing about them is that you can drop variables straight into the string without breaking it apart.

Here’s a full example so you can see it in action:

let name = "Hushbu";
let city = "Mumbai";

let message = `Hi ${name}, you live in ${city}. Nice to meet you!`;

console.log(message);

When you run it, you’ll get:

Hi Hushbu, you live in Mumbai. Nice to meet you!

You can also make multi-line strings with template literals, which keeps things easy to read.

If anything here feels unclear or you want more examples, I’m here to help.

Hi Kamohelo,

That error usually means you're trying to update something that doesn't exist in the DOM at the moment you're accessing it. In this case, you're trying to set the textContent of an element, but the variable holding that element is actually undefined.

This often happens when you're using something like element.children[2], but there are fewer than 3 children, so JavaScript can't find the item at index 2. Then, when you try to set textContent, it throws the error because you’re basically saying undefined.textContent = ..., which isn't valid.

Let’s say your code looks like this:

const priceList = document.querySelector("#price-list");
const update = document.querySelector("#update");

update.addEventListener("click", () => {
    const thirdItem = priceList.children[2];
    const thirdItemPrice = thirdItem.children[0];
    thirdItemPrice.textContent = "$4.00";
});

If thirdItem doesn’t exist, or if it doesn’t have a child at index 0, you’ll get that exact error.

To avoid it, you can add checks:

if (thirdItem && thirdItem.children.length > 0) {
    const thirdItemPrice = thirdItem.children[0];
    if (thirdItemPrice) {
        thirdItemPrice.textContent = "$4.00";
    } else {
        console.error("The child element you're trying to access doesn't exist.");
    }
} else {
    console.error("The third list item or its children do not exist.");
}

Also, using console.log() is super helpful — it lets you see what each variable actually holds before using it. That way, you can catch undefined values early and avoid these errors.

If you have more questions, I am here to help.

Hi George,

Good question — it confuses a lot of people at first.

When you use const with an array in JavaScript, you're saying the reference to the array can’t change — not the contents.

So this is allowed:

const fruits = ["Apple", "Banana", "Orange"];
fruits[1] = "Mango";  // ✅ You can update elements

But this is not allowed:

fruits = ["Grapes", "Pineapple"];  // ❌ Error: assignment to constant variable

So const just means you can’t assign a new array to that variable. You can still update, add, or remove elements from the original array.

If you have more questions, I am here to help.

Hi SALAAR,

The ` symbol is called a backtick.

On most keyboards, it is on the same key as ~ (tilde), usually near the top-left area of the keyboard. To type the backtick, press that key normally, without holding Shift. If you hold Shift, you will type ~ instead.

If your keyboard layout is different and you cannot find it, tell me what device you are using (Windows, Mac, or mobile) and your keyboard layout, and I can guide you to the exact key.

If you have more questions, I am here to help 😊

The . and # selectors are the keys to selecting elements in JavaScript.

In CSS selectors, a period(.) is used to target elements by their class name, while a hash(#) is used to select elements using their id.

When using JavaScript to manipulate HTML with document.querySelector(), these same selector mechanisms apply:

• Use document.querySelector('.className') to select elements by class.

• Use document.querySelector('#idName') to select elements by id.

Why might we choose class or id?

• If multiple elements share the same style or behavior, you typically use a class. Since classes involve multiple elements, document.querySelectorAll('.className') could be useful to select all occurrences.

• Ids, being unique, are great for elements that should stand out or be isolated. Only one element should have a particular id on a page.

Take a look at the following code:

// Target an element with a class of 'button'
const btn = document.querySelector(".button");

// Changes text content of elements of 'button' class
btn.textContent = "Claim Discount"

Since we've used a . selector here, the JS code targets the specified class (in this case, the button class).

Remember: It's all about how the HTML element has been marked up on your page!

Hi Tony Stark,

let is used to create a variable in JavaScript. It tells JavaScript to make a new named place to store a value.

Example:

let greeting = "Merry Christmas";

Now greeting holds that text, and you can use it later, or even change it:

greeting = "Happy New Year";

let is also block-scoped, meaning it only works inside the { } block where you created it, which helps avoid bugs.

If you have more questions, I am here to help 😊

Hi Jacob,

== compares values after JavaScript may convert one type to another (type coercion).
=== compares both the value and the type, with no conversion.

Example:

5 == "5"    // true (string "5" is converted to number)
5 === "5"   // false (number vs string)

Most of the time, === is safer because it avoids surprising conversions.

If you have more questions, I am here to help 😊