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JavaScript JavaScript Arrays Multidimensional Arrays Improve the Quiz – One Solution

Micah Angelica Baguio
Micah Angelica Baguio
3,108 Points

Improve the quiz - one solution

It keeps saying this: uncaught TypeError: incorrect.push is not a function at quiz.js:34:18 But that's exactly what the teacher did. I just don't understand why his works and mine doesn't?

const questions = [
  ['What is the nearest planet towards the Sun?', 'Mercury'],
  ['What is the second nearest planet towards the sun?', 'Venus'],
  ['What is the third nearest planet towards the sun?', 'Earth'],
  ['Name of the planet next to planet Earth', 'Mars']

]; 


// 1. Create a multidimensional array to hold quiz questions and answers


// 2. Store the number of questions answered correctly
const correct = 0;
const incorrect = 0;
let correctAnswers = 0;

/* 
  3. Use a loop to cycle through each question
      - Present each question to the user
      - Compare the user's response to answer in the array
      - If the response matches the answer, the number of correctly
        answered questions increments by 1
*/
for ( let i = 0; i < questions.length; i++ ) {   
  let question =  questions[i] [0];
     let answer = questions[i] [1];
     let response = prompt(question);

     if ( response === answer ) {
       correctAnswers++;
       correct.push(questions);
     } else {
       incorrect.push(questions);
     }
}

function createListItems( arr ) {
  let items = '';
  for ( let i = 0; i < arr.length; i++ ) {
    items += `<li>${ arr[i] [0] }, by ${ arr[i][1] } - ${ arr[i][2] }</li>`;
  }
  return items;
}

// 4. Display the number of correct answers to the user

let html = `
  <h1>You got ${correctAnswers} question(s) correct</h1>
  <h2>You got these questions right:</h2>
  <ol>${ createListItems(correct) }</ol>

  <h2>You got these questions wrong:</h2>
  <ol>${ createListItems(incorrect) }</ol>
`;

document.querySelector('main').innerHTML = html;

1 Answer

Steven Parker
Steven Parker
217,602 Points

The push method only exists on arrays, and in the video the variable incorrect is created as an array:

const incorrect = [];

But in this code, it is created as number:

const incorrect = 0;