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JavaScript JavaScript Basics Making Decisions in Your Code with Conditional Statements Boolean Values

Posted by Ruobing Zhang
Ruobing Zhang
1,409 Points

At 7:09 of the video, why you can just put line9 as: if ( correctGuess )?

At 7:09 of the video, why you can just put line9 as: if ( correctGuess )? What if the user didn't guess the number? Would it still console.log (' You guessed the number!') ?

2 Answers

Peter Vann
Peter Vann
36,427 Points

If statements use a conditional operator to determine program flow (if it evaluates to true, the code in the if statement's curly braces will execute, if it evaluates to false then it executes the else code, if there is any, or, if there is no else block, it will just skip the if block).

In effect:

( correctGuess === true )

will either evaluate to true or false, depending on the value of correctGuess. Consider this code:

if ( true ) {
  // will always execute
}

therefore, if correctGuess = true, then

if ( correctGuess ) {
  // will always execute
}

but if correctGuess = false, then

if ( correctGuess ) {
  // will NOT execute
} else {
  // will execute (if there is an else block)*
}
// *(otherwise) execution resumes here...

Does that make sense now?

I hope that helps. Happy coding!

Ruobing Zhang
Ruobing Zhang
1,409 Points

Thank you!

Peter Vann
Peter Vann
36,427 Points
Peter Vann
Peter Vann
36,427 Points

Another way to think of it relates to why the variable is named correctGuess in the first place (which is a very appropriate variable name for a boolean value, actually).

If it's true, then the guess is, in fact, CORRECT (DO go into the if block)

...whereas...

If it's false, then the guess is, in fact, INCORRECT (So, therefore, DON'T go into the if block, or run the ELSE code, if there is any)

Again, I hope that helps. Happy coding!

Peter Vann
Peter Vann
36,427 Points

In fact, you could probably improve the varible name to make the logic even more clear by renaming it to guess_is_correct.

Then the code would read:

if ( guess_is_correct ) { // === true
  // execute this code...
} else { // === false, and therefore, guess is NOT correct
 // then execute this code...
}

Again, I hope that helps. Happy coding!