JavaScript: Convert an object into a list of pairs

Last update on May 30 2022 10:02:48 (UTC/GMT +8 hours)

JavaScript Object: Exercise-15 with Solution

Write a JavaScript function to convert an object into a list of '[key, value]' pairs.

Sample Solution: -

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript function to convert an object into a list of pairs.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function key_value_pairs(obj) 
   {
    var keys = _keys(obj);
    var length = keys.length;
    var pairs = Array(length);
    for (var i = 0; i < length; i++) 
    {
      pairs[i] = [keys[i], obj[keys[i]]];
    }
    return pairs;
  }

function _keys(obj) 
  {
    if (!isObject(obj)) return [];
    if (Object.keys) return Object.keys(obj);
    var keys = [];
    for (var key in obj) if (_.has(obj, key)) keys.push(key);
    return keys;
  }
function isObject(obj) 
 {
    var type = typeof obj;
    return type === 'function' || type === 'object' && !!obj;
  }
console.log(key_value_pairs({red: "#FF0000", green: "#00FF00", white: "#FFFFFF"}));

Sample Output:

[["red","#FF0000"],["green","#00FF00"],["white","#FFFFFF"]]

Flowchart:

Live Demo:

See the Pen javascript-object-exercise-15 by w3resource (@w3resource) on CodePen.

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Next: Write a JavaScript function to get a copy of the object where the keys have become the values and the values the keys.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04