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Start your free trialEkaterina Svobodina
4,875 PointsJavaScript adds undifined when printing to the page.
So I haven't looked at the solution yet, because I want to understand why this code does what it does. It works, and print to the page what I want except it adds undefind:
This is what I want it to print:
You got 2 question(s) right. You got these question(s) correct:
How many states are there in the USA?
How many oceans are there?
You got these question(s) wrong:
- How many continents are there?
And this is what it prints:
You got 2 question(s) right. You got these question(s) correct: undefined
How many states are there in the USA?
How many oceans are there?
You got these question(s) wrong:
undefined
- How many continents are there?
Here is my code:
var qAndA = [
['How many states are there in the USA?', 51],
['How many continents are there?', 7 ],
['How many oceans are there?', 5]
];
//var q1 = parseInt(prompt(qAndA[0][0]));
//var q2 = parseInt(prompt(qAndA[1][0]));
//var q3 = parseInt(prompt(qAndA[2][0]));
var i;
var q;
var correct;
var notCorrect;
var correctN = 0;
var notCorrectN = 0;
var messageA;
var messageB;
for ( i = 0; i < qAndA.length; i += 1){
q = parseInt(prompt(qAndA[i][0]));
if (q === qAndA[i][1]) {
correctN +=1;
correct += '<p>' + correctN + '. ' + qAndA[i][0] + '</p>';
} else {
notCorrectN +=1;
notCorrect += '<p>' + notCorrectN + '. ' + qAndA[i][0] + '</p>';
}
}
function print(messageA) {
messageA = document.write('<div><h2>You got ' + correctN + ' question\(s\) right.</h2>' +
'<b> You got these question\(s\) correct: </b>' +
correct + '</div>' );
if (notCorrectN > 0) {
messageB = document.write(
'<p><b> You got these question\(s\) wrong: </b></p>' +
'<p>' + notCorrect + '</p>');
messageA += messageB;
}
return messageA;
}
print(messageA);
2 Answers
akak
29,445 PointsWhen you define variable like:
var i;
var q;
var correct;
var notCorrect;
its initial value is "undefined".
If you overwrite variable after declaration with a new value it's not a problem. But if you're going to concatenate, then you need to declare them initially as an empty string.
Ekaterina Svobodina
4,875 PointsThank you very much! It worked just like you said.