Building JSON object out of HTML elements value in javascript

Question

So right now i have the following in my page:

where it consists of a dropdown menu and an input text field. So what I want is to create a JSON formatted object in javascript from the HTML elements above so I would get something like:

myObj = {
   Name: Jake,
   Address: 51 Lake District
}

However the method I'm using right now is sort of inefficient where i did it like:

var myObj = {
   [document.getElementById("drop1").value]:document.getElementById("n_in").value,
   [document.getElementById("drop2").value]:document.getElementById("a_in").value,
}
console.log(JSON.stringify(myObj))

I'm not entirely sure if this is a good way of doing it, but in the future if i were to add another set of fields like a "Country" dropdown in the HTML, I would have to hard code another field into the variable above again.

Is this a good way of doing it?

var myObj = {
    [document.getElementById("drop1").value]:document.getElementById("n_in").value,
    [document.getElementById("drop2").value]:document.getElementById("a_in").value,
 }
console.log(JSON.stringify(myObj))

<!DOCTYPE html>
<html lang="en">  
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  
  <title>Document</title>
</head>
<body>
  <div id="lst">
    <div class = "ifield">
      <select id = "drop1">
        <option value = "Name">Name</option>
      </select>
      <input type = "text" id = "n_in" value = "Jake">
    </div>
    <div class = "ifield">
      <select id = "drop2">
          <option value = "Address">Address</option>
      </select>
      <input type = "text" id = "a_in" value = "51 Lake District">
  </div>
  </div>
  <script src = "test.js"></script>
  </body>
</body>
</html>

Robby Cornelissen · Accepted Answer · 2020-11-16 02:30:07Z

2

You could select all your .ifield elements and reduce() them to an object:

const values = [...document.querySelectorAll('.ifield')].reduce((a, v) => {
  a[v.querySelector('select').value] = v.querySelector('input').value;
  return a;
}, {});

console.log(values);

<div id="lst">
  <div class="ifield">
    <select id="drop1">
      <option value="Name">Name</option>
    </select>
    <input type="text" id="n_in" value="Jake">
  </div>
  <div class="ifield">
    <select id="drop2">
      <option value="Address">Address</option>
    </select>
    <input type="text" id="a_in" value="51 Lake District">
  </div>
</div>

answered Nov 16, 2020 at 2:30

Robby Cornelissen

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3 Comments

Maxxx Over a year ago

thank you. May i ask what is the three dots for in the [...document.querySelectorAll]?

Robby Cornelissen Over a year ago

Spread syntax. Using it to convert the list of elements (which is a NodeList) to an array.

Maxxx Over a year ago

sorry, I would like to ask, if I would like a mix of both 'input' and 'textarea', such as in the Address field where instead of a input text, i would opt for a textarea element instead, would it be just a[v.querySelector('select').value] = v.querySelector('input, textarea').value?

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