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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

Anytime. Enjoy the journey!

1 Answer

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

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

Anytime. Enjoy the journey!