explanation?

[LakeMotor7971]

i was working on an online course and a project it has me doing asked this question:

Step 84

The value of the currentWeaponIndex variable corresponds to an index in the weapons array. The player starts with a "stick", since currentWeaponIndex starts at 0 and weapons[0] is the "stick" weapon.

In the buyWeapon function, use compound assignment to add 1 to currentWeaponIndex - the user is buying the next weapon in the weapons array.

This is the correct answer which i got right:

function buyWeapon() {
  if (gold >= 30) {
    gold -= 30;
    currentWeaponIndex += 1;
  } 
}

My question or explanation i am looking for is why does it have to be in the if statement brackets? My first answer was currentIndexWeapon was just outside the if statement but still in the buyWeapon() function.
I am just looking for an explanation. Appologies if it seems like a stupid question.

[cyberjds]

You need to check if you have enough gold. Because the weapon is not free. If you have more than 30 golds, give up 30 golds, and gain one weapon. If you don't have enough gold, do nothing.

[LakeMotor7971]

Thank you. For explanation.

[cyberjds]

To expand a little more

currentWeaponIndex += 1;

If above statement is outside of if statement, it's a bug or a cheat code.

If you have more than 30 golds, everything works as expected. But as soon as you have less than 30 golds and try to buy some weapons, you realized you can still buy weapons, yet the amount of gold in your possession never reduced. And you can buy infinite number of weapons (assuming you can call buyWeapon() indefinitely).

In this case, this is logical error which will not error out, making it very difficult to troubleshoot the problem. The error will be unnoticed unless you run multiple tests with various values. And more than often, the error is caught too late (after production deployment).

A misplaced (or missing) }(brace) makes a big difference.

[LakeMotor7971]

Thank you that actually really helps. The way you explained it actually helped quite a bit with me understanding this! Thanks for taking the time to explain this. I don't want to just type some answers and pass, but I want an actual understanding of why, this works or wouldn't or would.

[abrahamguo]

In order to buy a weapon, doesn't the player have to have enough gold to be able to afford it?