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Igor Lamarain Montes
4,405 PointsI dont understand why i get this message.(quiz.js:14 Uncaught TypeError: Cannot read property '1' of undefined(…))
function print(message) {
document.write(message);
}
questions=[
['where do you live?','Madrid'],
['what is the color of the chair?','blue'],
['what car do you have?','none']
];
var solution=[];
var wrong=[];
for(var i=0;i<=3;i++){
if( questions[i][1]==prompt(questions[i][0])) {
solution.push(questions[i][1]);
}else wrong.push(questions[i][1]);
}
document.write('<p> You have solution.length </p>');
2 Answers
Ted Dunn
43,783 PointsThe problem is in your for loop. You have the conditional expression checking if i <= 3 but there are only three elements in your questions array which means that the elements are indexed as 0, 1, 2. There is no element with an index of 3 in your array so you are trying to access a record that isn't there when your i variable is equal to 3.
To fix this you need to change the expression to i < 3 (or i <= 2) or as a best practice you should compare it to the lenght of the questions[] array (questions.length) , so that if you add questions in the future the expression will still be valid.
In summary, the best way to write your for loop conditional is as follows:
for (var i = 0, i < questions.length; i++)
Igor Lamarain Montes
4,405 PointsO great, thank you Ted.