Understanding Variables in Javascript Tutorial

After diving into the tutorials here, I find myself struggling to grasp some elements of this example. Why is the variable initialized as an empty string and what does the ,i signify?

var x="",i;

Furthermore, why the need for

 x=x

at the start of the line?

<!DOCTYPE html>
<html>
<body>

<p>Press the button to iterate from 1 to 6, creating HTML headings.</p>
<button onclick="myFunction()">Try it</button>
<div id="demo"></div>

<script>
function myFunction()
{
var x="",i;
for (i=1; i<=6; i++)
{
 x=x + "<h" + i + ">Heading " + i + "</h" + i + ">";
}
document.getElementById("demo").innerHTML=x;
}
</script>

</body>
</html>

Answer №1

let a = "", b;

When you see this code, it means

let a = "";
let b;

This is simply defining those variables within the scope they are in.

a = a + ...

This indicates that you should update the value of variable a with the result of the expression on the right side of the = sign. In this scenario, you are appending a string to the existing value of variable a.

Answer №2

let message = "", count;

can be written as

let message = "";
let count;

When declaring variables like this:

let alpha = 1,
    beta = 2,
    gamma = 3;

It is a common practice that enhances code readability and organization.

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