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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops A Closer Look At Loop Conditions

Rob Bartlett
Rob Bartlett
6,741 Points
Posted by Rob Bartlett
Rob Bartlett
6,741 Points

Using a Function to Make This Cleaner

Ok, so I was able to pass this challenge by writing 

var secret = prompt("What is the secret password?");
var entry = "sesame";

while (secret !== entry) {
  secret = prompt("That is incorrect. What is the secret password?")
}

document.write("You know the secret password. Welcome.");

However, I had hoped to save myself the trouble of re-writing the variable and prompt by using a function (as well as exercise a more elegant solution). What I tried was:

function gatekeeper() {
  var secret = prompt("What is the secret password?")};
var entry = "sesame";
gatekeeper ();

while (secret.toLowerCase !== entry) {
  gatekeeper ();
}

document.write("You know the secret password. Welcome.");

I call gatekeeper before getting into the loop to establish var secret, but then once it gets to the while loop, I get the error that secret is undefined.

What gives?

4 Answers

Grove Software
Grove Software
1,508 Points
Grove Software
Grove Software
1,508 Points

The variable secret is scoped to the gatekeeper function, which means that anything outside the function can't see it. To be honest, even if you fixed that by declaring secret outside of the gatekeeper function, I'm not sure I'd call that more elegant solution.

Rob Bartlett
Rob Bartlett
6,741 Points
Rob Bartlett
Rob Bartlett
6,741 Points

Well, more elegant in the sense that I'm avoiding repeating a line of code.

Grove Software
Grove Software
1,508 Points
Grove Software
Grove Software
1,508 Points

Sometimes trying to avoid repeating yourself can be taken too far. You've ultimately repeated the variable in the form of calling gateKeeper multiple times.

Colin Marshall
Colin Marshall
32,861 Points
Colin Marshall
Colin Marshall
32,861 Points

This is because of the variable scope of secret. You declared secret inside of the gatekeeper function. Since you did this, only the code inside of the function has access to that variable.

Rob Bartlett
Rob Bartlett
6,741 Points
Rob Bartlett
Rob Bartlett
6,741 Points

I figured that was the case. So, is there a way to make this work by just calling a function in the loop? Is the solution here simply to make the loop part of the function?

Jacob Mishkin
Jacob Mishkin
23,117 Points
Jacob Mishkin
Jacob Mishkin
23,117 Points

There are several things that this challenge is doing:

  1. understanding how the while loop works.
  2. understanding the conditional statement.

For number 1. from what you posted it seems like you understand this concept. While loop: While the condition is false do something.

For number 2. Let the conditional statement do the work for you. What I mean by that is, you don't need to set variables outside to set the condition to be true or false, that's the job of the statement itself. So in this case we are just checking if an input field equals a string, just add the string in the condition. No need for a new variable to be processed.

here is an example: 

var secret = prompt("what is the secret  password");
while (secret !== "sesame") {
  secret = prompt("That is incorrect. What is the secret password?")
}
document.write("You know the secret password. Welcome.");

if you have any questions please ask.

Colin Marshall
Colin Marshall
32,861 Points
Colin Marshall
Colin Marshall
32,861 Points

One issue I see with your example is that if you leave the secret variable empty when you declare it, you will be told you guessed incorrectly before you have had a chance to guess the password.

Jacob Mishkin
Jacob Mishkin
23,117 Points

Colin, I see your point. I will make the changes. thanks.

Grove Software
Grove Software
1,508 Points
Grove Software
Grove Software
1,508 Points

If you did something like:

function gatekeeper() {
  var secret = prompt("What is the secret password?");
  var entry = "sesame";
  return secret === entry;
}

while (! gatekeeper()) {
}

document.write("You know the secret password. Welcome.");

That might work. I'm not certain of how the while loop would react to having a blocking operation in it like that.