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JavaScript JavaScript Basics (Retired) Making Decisions with Conditional Statements The Conditional Challenge

Posted by Steve Tenpas
Steve Tenpas
6,234 Points

Can a variable === a variable?

Why doesn't this add one to the correctAnswer variable?

var correctAnswer = 0;
var answer1 = 2;
var guess1 = prompt("What is 1 + 1?");
if (guess1 === answer1){
  correctAnswer += 1;
}
document.write(correctAnswer);

this works if I write

if(guess1 === 2)

...but shouldn't it also work the other way? I am missing something. Any help would really be appreciated.

Jeff Lemay
Jeff Lemay
14,268 Points
Jeff Lemay
Jeff Lemay
14,268 Points

Anytime. Enjoy the journey!

1 Answer

Jeff Lemay
Jeff Lemay
14,268 Points
Jeff Lemay
Jeff Lemay
14,268 Points

Three equal signs like you have will compare the value and type. So you are comparing an integer (the answer) to a string (the guess). Two equal signs will only compare the value which is what you'll want to use here.

In-depth learning: http://stackoverflow.com/questions/359494/does-it-matter-which-equals-operator-vs-i-use-in-javascript-comparisons

Steve Tenpas
Steve Tenpas
6,234 Points

Thanks Jeff. I appreciate your help. The stackoverflow resource helpful as well. Is the "guess", which in this case is the response to the prompt("What is 1 + 1?"), always a string?

Jeff Lemay
Jeff Lemay
14,268 Points
Jeff Lemay
Jeff Lemay
14,268 Points

It doesn't have to be a string. You can use parseInt() to turn the value into an integer before you run it through your if statement.

Resource: http://stackoverflow.com/questions/1133770/how-do-i-convert-a-string-into-an-integer-in-javascript

var correctAnswer = 0;
    answer1 = 2;
    guess1 = prompt("What is 1 + 1?");
    guess1 = parseInt(guess1);

if (guess1 === answer1){
  correctAnswer += 1;
}
document.write(correctAnswer);
Steve Tenpas
Steve Tenpas
6,234 Points

Alright, thanks. I tried the parseInt(guess1) but made the mistake of putting it inside the if statement. This is very helpful. I appreciate your advice.

Jeff Lemay
Jeff Lemay
14,268 Points
Jeff Lemay
Jeff Lemay
14,268 Points

Anytime. Enjoy the journey!