I want to put some key value in javascript json object dynamically

Question

Here the value of i is temp, hum. but when i want to put the value of i in " myObj.i[j]; " then it is giving me the error:

Uncaught TypeError: Cannot read property '0' of undefined at json_trial.html:21

while I am doing x=myObj.temp[j]; it is working fine. I don't want to use it directly, I want to use it dynamically. Please help

<!DOCTYPE html>
<html>
  <body>
    <p>Access an array value of a JSON object.</p>

    <p id="demo"></p>

    <script>
      var myObj, x;
      myObj = {
        "temp": ["Temperature", "22.8", "℃"],
        "hum": ["Humidity", "48.8", "%"]
      };

      for (var i in myObj) {
        alert(i);
        for (var j = 0; j < 3; j++) {
          x = myObj.i[j];
          alert(x);
          document.getElementById("demo").innerHTML = x;

        }
      }

      //x = myObj._1[2];
      //document.getElementById("demo").innerHTML = x;

    </script>
  </body>
</html>

use bracket notation for both properties: `x=myObj[i][j];` – Nick Parsons Sep 06 '19 at 12:27 — Nick Parsons, Sep 06 '19 at 12:27

score 0 · Answer 1 · edited Sep 06 '19 at 12:43

I added code for showing the data properly.

<!DOCTYPE html>
<html>
  <body>
    <p>Access an array value of a JSON object.</p>

    <p id="demo"></p>

    <script>
      var myObj, x;
      myObj = {
        "temp": ["Temperature", "22.8", "℃"],
        "hum": ["Humidity", "48.8", "%"]
      };

      for (var i in myObj) {
        alert(i);
        for (var j = 0; j < 3; j++) {
          x = myObj[i][j];
          alert(x);
          document.getElementById("demo").innerHTML = x;

        }
      }

      //x = myObj._1[2];
      //document.getElementById("demo").innerHTML = x;

    </script>
  </body>
</html>

score 0 · Accepted Answer · answered Sep 06 '19 at 12:35

This code must work perfectly.

  <!DOCTYPE html>
  <html>
  <body>
    <p>Access an array value of a JSON object.</p>

    <p id="demo"></p>

    <script>
      var myObj, x='';
      myObj = {
        "temp": ["Temperature", "22.8", "℃"],
        "hum": ["Humidity", "48.8", "%"]
      };

      for (var i in myObj) {
          x += myObj[i].join(' ');
          x += '<br/>';
          document.getElementById("demo").innerHTML = x;
      }

      //x = myObj._1[2];
      //document.getElementById("demo").innerHTML = x;

    </script>
  </body>
</html>

score 0 · Answer 3 · answered Sep 06 '19 at 12:38

remember that "i" is a variable, so, if you need use a variable like to key, in a object, you need use the variable between [].

For example:

for(var i in myObj){
 for(var j = 0; j < myObj[i].length; j++){
  var element = myObj[i][j];
  console.log(element)
 }
}

Thanks.

I want to put some key value in javascript json object dynamically

3 Answers3