How to check for a string === null? In this video, Dave writes "Search === null". This doesn't work for me.

Strange. I'll have to look at this further on Monday because I know it worked at my work machine (Mac). I have Windows at home - not sure if that makes a difference. In the video Dave doesn't declare search with var or let. I removed your loop and declared name with let instead of var

    console.log('start');
    let name = prompt("Enter a student name to search (quit to stop)");

    if (name === null) {
        console.log("===null " + name);
    }
    if (name) {
        console.log("name " + name);
    }
    if (!name) {
        console.log("!name " + name);
    }
    if (name != null) {
        console.log("!=null " + name);
    }
    if (name !== null) {
        console.log("!==null " + name);
    }
    console.log('end');

and cancelling the result is:

start
===null null
!name null
end

If I use var or no keyword to declare name the result is:

start
name null
!=null null
!==null null
end

interesting! I am using Windows 10 and Chrome. What I found is even stranger.

This works:

if (name.toUpperCase() === "NULL") 

using let in a while (true) works with a break statement. I can't get a Do While loop to work. This is kind of crazy but at least I know how to make it work.

I think the let statement can't work in a Do While because While is outside the {}.

Thank you for your help Kris. I'm curious what you find as well.

I just read: https://developer.mozilla.org/en-US/docs/Web/API/Window/prompt

"Please note that result is a string. " <- I am assuming this is a weirdness of JavaScript or a bug. null in JS is type Object not type String, which explains why the below code works. It's a little maddening to my brain...

if (name.toUpperCase() === "NULL") 

any thoughts?

thank you again for your help Kris!

I apologize if I am over posting. This code ends up allowing me to do what I believe is the correct way to check for null. If I use var I get name as a typeOf string. Even if I set it explicitly to null. If I use let. I has to be declared outside of the loop for scope. BUT it does start out as typeOf object (which is what null is).

let equals true null value

let name = null;
do {
    console.log("begin DO");

    console.log(name);
    console.log(typeof (name));

    name = prompt("Enter a student name to search (quit to stop)");

    console.log(name);
    console.log(typeof (name));

    if (name) {
        console.log("name " + name);
    }
    if (!name) {
        console.log("!name " + name);
    }

} while (name && name.toUpperCase() !== "QUIT");
console.log("end DO");
console.log(name);

var equals type of string even when setting to null or not declaring a value

var name = null;
//or var name; //<- same result - typeOf string
do {
   same code here

Great to know! I didn't even think of my variable name being an issue!