Why do i not get the output I expect in this simple JS if statement

Question

I am a JS beginner. Just read a couple of beginner books. I am now taking an online course and even though I thought I knew if statements this bit of code doesn't seem to run right.

Here is the simple code that is taken directly from the course teaching materials:

let stationery = "pen";
if (stationery == "pen" || "pencil") { 
    console.log("You have enough stationery to write the exam.");
}
else {
    console.log("You do not have sufficient stationery to write the exam.");
}

On the face of it it seems ok. When I see console.log the output say: You have enough stationery to write the exam.

However, if I change the stationery variable to something else like "chalk" and rerun the if statement, the console.log result still says: You have enough stationery to write the exam.

I would expect the final else statement to kick in and show: You do not have sufficient stationery to write the exam.

This is so early on in the course that I am almost embarrassed to ask. What am I missing? The beginner books I read were before let and used var. Is it anything to do with this that is confusing my beginner's understanding?

I think this could be something to do with "truthy" values in the if statement conditionals but I don't get it.

Thanks.

Answer 1

Your conditional is wrong, it always will return a true value, because "pencil" is a truthy value, https://developer.mozilla.org/en-US/docs/Glossary/Truthy#:~:text=In%20JavaScript%2C%20a%20truthy%20value,type%20coercion%20in%20Boolean%20contexts.

let stationery = "pen";
if (stationery == "pen" || "pencil") { 
    console.log('this is always true')
}

Maybe this is the logic you are looking for:

let stationery = "pen";
if (stationery == "pen" || stationery ==  "pencil") { 
    // ...
}