What is the most effective way to access nested elements by index in JavaScript?

Question

What is the most effective way to access nested elements by index in JavaScript?

I am looking to design a user-friendly form that presents questions for users to navigate, revealing different answers/questions based on their responses. For example:

var json = 
     {
      "Did you restart the computer?": [
        {
          "Yes": [
            {
              "Is the software running?": [
                {
                  "Yes": "Cannot help",
                  "No": "Open it"
                }
              ]
            }
          ],
          "No": "Please restart it"
        }
      ]
    }

Is there a more efficient data structure than accessing options by keys like json["Did you restart the computer?"][0]["Yes"] and json["Did you restart the computer?"][0]["No"]?

If a user selects "Yes" for the first question, I know I can access keys like this:

Object.keys(json["Did you restart the computer?"][0]["Yes"][0])
>> ['Is the software running?']

And if they select "Yes" again:

Object.keys(json["Did you restart the computer?"][0]["Yes"][0]["Is the software connected to the server?"][0])
>> (2) ['Yes', 'No']

However, this method seems complex. Is there a simpler way to access keys/values using indexes (e.g., json[0][0][1])?

javascript json data-structures nested

Answer 1

Answer №1

Based on Bergi's feedback, there is no need for arrays; instead, simply utilize "Yes" and "No" as keys

document.addEventListener('DOMContentLoaded', () => {
  const questionElement = document.getElementById('question');
  const yesBtn = document.getElementById('yesBtn');
  const noBtn = document.getElementById('noBtn');

  let currentStep = paths;

  const updateQuestion = () => {
    const isFinalAnswer = typeof currentStep === 'string';
    questionElement.innerHTML = isFinalAnswer ? currentStep : Object.keys(currentStep)[0];
    yesBtn.hidden = isFinalAnswer;
    noBtn.hidden = isFinalAnswer;
  };

  document.getElementById('container').addEventListener('click', (e) => {
    if (e.target.id === 'yesBtn' || e.target.id === 'noBtn') {
      const response = e.target.id === 'yesBtn' ? 'Yes' : 'No';
      const question = Object.keys(currentStep)[0];

      if (currentStep[question] && currentStep[question][response]) {
        currentStep = currentStep[question][response];
        updateQuestion();
      }
    }
  });

  updateQuestion();
});

#container {
  text-align: center;
  margin-top: 50px;
}

#question {
  margin-bottom: 20px;
}

.btn {
  margin: 5px;
  padding: 10px 20px;
  cursor: pointer;
}

<div id="container">
  <div id="question"></div>
  <button class="btn" id="yesBtn" hidden>Yes</button>
  <button class="btn" id="noBtn" hidden>No</button>
</div>

<script>
  const paths = {
    "Did you restart the computer?": {
      "Yes": {
        "Is the software running?": {
          "Yes": "Cannot help",
          "No": "Open it"
        }
      },
      "No": "Please restart it"
    }
  };
</script>

Prior solution:

document.addEventListener('DOMContentLoaded', () => {
  const questionElement = document.getElementById('question');

  let currentStep = paths[0]; // start

  const updateQuestion = () => {
    const isString = typeof currentStep === 'string';
    questionElement.innerHTML = isString ? currentStep : currentStep.question;
    yesBtn.hidden = isString;
    noBtn.hidden = isString;
  };

  document.getElementById('container').addEventListener('click', (e) => {
    const which = e.target.id === 'yesBtn' ? 0 : 1
    if (currentStep.answers && currentStep.answers[which]) {
      const next = currentStep.answers[which].next;    
      currentStep = Array.isArray(next) ? next[0] : next;
      updateQuestion();
    }
  });
  updateQuestion();
});

#container {
  text-align: center;
  margin-top: 50px;
}

#question {
  margin-bottom: 20px;
}

.btn {
  margin: 5px;
  padding: 10px 20px;
  cursor: pointer;
}

<div id="container">
  <div id="question"></div>
  <button class="btn" id="yesBtn" hidden>Yes</button>
  <button class="btn" id="noBtn" hidden>No</button>
</div>

<script>
  const paths = [{
    "question": "Did you restart the computer?",
    "answers": [{
        "response": "Yes",
        "next": [{
          "question": "Is the software running?",
          "answers": [{
              "response": "Yes",
              "next": "Cannot help"
            },
            {
              "response": "No",
              "next": "Open it"
            }
          ]
        }]
      },
      {
        "response": "No",
        "next": "Please restart it"
      }
    ]
  }];
</script>

Answer 2

Based on Bergi's feedback, there is no need for arrays; instead, simply utilize "Yes" and "No" as keys

document.addEventListener('DOMContentLoaded', () => {
  const questionElement = document.getElementById('question');
  const yesBtn = document.getElementById('yesBtn');
  const noBtn = document.getElementById('noBtn');

  let currentStep = paths;

  const updateQuestion = () => {
    const isFinalAnswer = typeof currentStep === 'string';
    questionElement.innerHTML = isFinalAnswer ? currentStep : Object.keys(currentStep)[0];
    yesBtn.hidden = isFinalAnswer;
    noBtn.hidden = isFinalAnswer;
  };

  document.getElementById('container').addEventListener('click', (e) => {
    if (e.target.id === 'yesBtn' || e.target.id === 'noBtn') {
      const response = e.target.id === 'yesBtn' ? 'Yes' : 'No';
      const question = Object.keys(currentStep)[0];

      if (currentStep[question] && currentStep[question][response]) {
        currentStep = currentStep[question][response];
        updateQuestion();
      }
    }
  });

  updateQuestion();
});

#container {
  text-align: center;
  margin-top: 50px;
}

#question {
  margin-bottom: 20px;
}

.btn {
  margin: 5px;
  padding: 10px 20px;
  cursor: pointer;
}

<div id="container">
  <div id="question"></div>
  <button class="btn" id="yesBtn" hidden>Yes</button>
  <button class="btn" id="noBtn" hidden>No</button>
</div>

<script>
  const paths = {
    "Did you restart the computer?": {
      "Yes": {
        "Is the software running?": {
          "Yes": "Cannot help",
          "No": "Open it"
        }
      },
      "No": "Please restart it"
    }
  };
</script>

Prior solution:

document.addEventListener('DOMContentLoaded', () => {
  const questionElement = document.getElementById('question');

  let currentStep = paths[0]; // start

  const updateQuestion = () => {
    const isString = typeof currentStep === 'string';
    questionElement.innerHTML = isString ? currentStep : currentStep.question;
    yesBtn.hidden = isString;
    noBtn.hidden = isString;
  };

  document.getElementById('container').addEventListener('click', (e) => {
    const which = e.target.id === 'yesBtn' ? 0 : 1
    if (currentStep.answers && currentStep.answers[which]) {
      const next = currentStep.answers[which].next;    
      currentStep = Array.isArray(next) ? next[0] : next;
      updateQuestion();
    }
  });
  updateQuestion();
});

#container {
  text-align: center;
  margin-top: 50px;
}

#question {
  margin-bottom: 20px;
}

.btn {
  margin: 5px;
  padding: 10px 20px;
  cursor: pointer;
}

<div id="container">
  <div id="question"></div>
  <button class="btn" id="yesBtn" hidden>Yes</button>
  <button class="btn" id="noBtn" hidden>No</button>
</div>

<script>
  const paths = [{
    "question": "Did you restart the computer?",
    "answers": [{
        "response": "Yes",
        "next": [{
          "question": "Is the software running?",
          "answers": [{
              "response": "Yes",
              "next": "Cannot help"
            },
            {
              "response": "No",
              "next": "Open it"
            }
          ]
        }]
      },
      {
        "response": "No",
        "next": "Please restart it"
      }
    ]
  }];
</script>

Answer 3

Answer №2

In my opinion, this question may not be the best fit for StackOverflow due to potential subjective responses. In order to access objects by keys and utilize indexes effectively, it is recommended to use an array structure and avoid including text elements within your data structure. Consider structuring your data like the following example:

const options = [
  {
    type: "question",
    text: "Have you done this?",
    yes: {
      text: "Yes",
      options: [{
        type: "question",
         text: "Is the software running?",
         yes: {
           text: "Yes",
           options: [{
             type: "message",
             text: "Can't help",
           }]
         },
        no: {
          text: "No",
          options: [{
            type: "message",
            text: "Call for help",
          }]
        }
      }]
    },
    no: {
      type: "question",
      text: "No",
      options: [{
        type: "question",
        text: "have you tried this other thing?",
        options: [
          `...`
        ]
      }]
    }
  }
]

By accessing

options[0].yes.options[0].yes.options[0].text

, you will get Can't help.

Answer 4

In my opinion, this question may not be the best fit for StackOverflow due to potential subjective responses. In order to access objects by keys and utilize indexes effectively, it is recommended to use an array structure and avoid including text elements within your data structure. Consider structuring your data like the following example:

const options = [
  {
    type: "question",
    text: "Have you done this?",
    yes: {
      text: "Yes",
      options: [{
        type: "question",
         text: "Is the software running?",
         yes: {
           text: "Yes",
           options: [{
             type: "message",
             text: "Can't help",
           }]
         },
        no: {
          text: "No",
          options: [{
            type: "message",
            text: "Call for help",
          }]
        }
      }]
    },
    no: {
      type: "question",
      text: "No",
      options: [{
        type: "question",
        text: "have you tried this other thing?",
        options: [
          `...`
        ]
      }]
    }
  }
]

By accessing

options[0].yes.options[0].yes.options[0].text

, you will get Can't help.

What is the most effective way to access nested elements by index in JavaScript?

Answer №1

Answer №2

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