Lets break it into steps:

(1) The Basics: Array Access

In JavaScript, arrays are zero-indexed, meaning the first element is accessed with index 0, the second with 1, and so on. So, if we have an array like [9,8,7,6], accessing the element at index 1 should give us 8. That's straightforward, right?

const myArray = [5,9,7,4,6]; 
const elementAtIndex1 = myArray[1]; 
// Result: elementAtIndex1 = 9

(2) The Curiosity: Comma Operator

In JavaScript, the comma operator , is a bit of an unsung hero. It evaluates multiple expressions and returns the value of the last one.

Example:

const resultOfCommaOperator = (1, 2); 
// Result: resultOfCommaOperator = 2

Here, (1, 2) uses the comma operator. It evaluates 1, then 2, and returns the value of the last one, which is 2. Simple, right?

Unpack the mystery:

Now, let's connect it to our original puzzle:

const finalResult = [5,9,7,5,6][1, 2]; 
// (1):comma operator will take effect
//(2):original expression now looks like `[5,9,7,4,6][2]`
// Result: finalResult = 7`

The expression [1, 2] inside the square brackets gets evaluated first, and thanks to the comma operator, it becomes just 2. So, our original expression now looks like [5,9,7,5,6][2], and that gives us the result 7.

In essence, the comma operator helped us simplify the array access, turning [1, 2] into a single value, making the final result 7.

JavaScript's quirks can be amusing, and understanding these little intricacies adds to the fun of programming! 😊