Adding new key value in nested array based on parent value

Question

I have an array with Questions. Each question has options to pick from and the correct answer. I am trying to add true/false if the option is correct. How should I best do this? I tried .map() and .forEach but I don't know how to access correct_answer and use that to add the true/false values under options.

const data = [
    {
        "question": "What is the approximate value of mathematical constant e?",
        "options": [
            {
                "option": "1.41",
            },
            {
                "option": "1.62",
            },
            {
                "option": "2.72",
            },
            {
                "option": "3.14",
            }
        ],
        "correct_answer": "2.72"
    },
    {
        "question": "What is the name of the main character of the anime &quot;One-Punch Man&quot;?",
        "options": [
            {
                "option": "Genos",
            },
            {
                "option": "King",
            },
            {
                "option": "Saitama",
            },
            {
                "option": "Sonic",
            }
        ],
        "correct_answer": "Saitama"
    }
]

Desired result

const data = [
    {
        "question": "What is the approximate value of mathematical constant e?",
        "options": [
            {
                "option": "1.41",
                "correct_answer": false,
            },
            {
                "option": "1.62",
                "correct_answer": false,
            },
            {
                "option": "2.72",
                "correct_answer": true,
            },
            {
                "option": "3.14",
                "correct_answer": false,
            }
        ],
        "correct_answer": "2.72"
    },
    {
        "question": "What is the name of the main character of the anime &quot;One-Punch Man&quot;?",
        "options": [
            {
                "option": "Genos",
                "correct_answer": false,
            },
            {
                "option": "King",
                "correct_answer": false,
            },
            {
                "option": "Saitama",
                "correct_answer": true,
            },
            {
                "option": "Sonic",
                "correct_answer": false,
            }
        ],
        "correct_answer": "Saitama"
    }
]

Kinglish · Accepted Answer · 2022-12-01 20:21:59Z

You can use Array.map to update the values and the spread operator to populate the objects.

let newdata = data.map(d => ({ ...d,
  options: d.options.map(m => ({ ...m,
    correct_answer: m.option == d.correct_answer ? true : false
  }))
}))

const data = [{
    "question": "What is the approximate value of mathematical constant e?",
    "options": [{
        "option": "1.41",
      },
      {
        "option": "1.62",
      },
      {
        "option": "2.72",
      },
      {
        "option": "3.14",
      }
    ],
    "correct_answer": "2.72"
  },
  {
    "question": "What is the name of the main character of the anime &quot;One-Punch Man&quot;?",
    "options": [{
        "option": "Genos",
      },
      {
        "option": "King",
      },
      {
        "option": "Saitama",
      },
      {
        "option": "Sonic",
      }
    ],
    "correct_answer": "Saitama"
  }
]

let newdata = data.map(d => ({ ...d,
  options: d.options.map(m => ({ ...m,
    correct_answer: m.option == d.correct_answer ? true : false
  }))
}))

console.log(newdata)

Konrad · Accepted Answer · 2022-12-01 20:15:26Z

const data = [{
    "question": "What is the approximate value of mathematical constant e?",
    "options": [{
        "option": "1.41",
      },
      {
        "option": "1.62",
      },
      {
        "option": "2.72",
      },
      {
        "option": "3.14",
      }
    ],
    "correct_answer": "2.72"
  },
  {
    "question": "What is the name of the main character of the anime &quot;One-Punch Man&quot;?",
    "options": [{
        "option": "Genos",
      },
      {
        "option": "King",
      },
      {
        "option": "Saitama",
      },
      {
        "option": "Sonic",
      }
    ],
    "correct_answer": "Saitama"
  }
]

data.forEach(question => {
  question.options.forEach(option => {
    option.correct_answer = option.option === question.correct_answer
  })
})

console.log(data)

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