Wednesday, January 21, 2026
HomeLanguagesJavascriptHow to add key/value pair to a JavaScript object ?

How to add key/value pair to a JavaScript object ?

In order to add key/value pair to a JavaScript object, Either we use dot notation or square bracket notation. Both methods are widely accepted. 

Example 1: This example adds {“nextFavColor” : “red”} to the GFG_p object by using dot notation

html




<h1 style="color:green;">
    GeeksForGeeks
</h1>
 
<p id="GFG_up" style="color:red;"></p>
 
<button onclick="Geeks()">
    Click to add
</button>
 
<p id="GFG_down" style="color:green;"></p>
 
<script>
    var GFG_p = {fName:"Geeks", lName:"forGeeks",
                age:100, favColor:"green"};
    var p_up = document.getElementById("GFG_up");
    var p_down = document.getElementById("GFG_down");
    p_up.innerHTML = JSON.stringify(GFG_p);
      
    function Geeks() {
        GFG_p.nextFavColor = "Red";
        p_down.innerHTML = JSON.stringify(GFG_p);    
    }
</script>


Output:

 

Example 2: This example adds {“thirdFavColor” : “blue”} to the GFG_p object by using square bracket notation

html




<h1 style="color:green;">
    neveropen
</h1>
  
<p id="GFG_up" style="color:blue;"></p>
  
<button onclick="Geeks()">
    Click to add
</button>
  
<p id="GFG_down" style="color:green;"></p>
  
<script>
    var GFG_p = {fName:"Geeks", lName:"forGeeks",
                age:100, favColor:"green"};
    var p_up = document.getElementById("GFG_up");
    var p_down = document.getElementById("GFG_down");
    p_up.innerHTML = JSON.stringify(GFG_p);
      
    function Geeks() {
        GFG_p["thirdFavColor"] = "blue";
        p_down.innerHTML = JSON.stringify(GFG_p);    
    }
</script>


Output:

 

RELATED ARTICLES

Most Popular

Dominic
32475 POSTS0 COMMENTS
Milvus
119 POSTS0 COMMENTS
Nango Kala
6847 POSTS0 COMMENTS
Nicole Veronica
11977 POSTS0 COMMENTS
Nokonwaba Nkukhwana
12064 POSTS0 COMMENTS
Shaida Kate Naidoo
6986 POSTS0 COMMENTS
Ted Musemwa
7220 POSTS0 COMMENTS
Thapelo Manthata
6933 POSTS0 COMMENTS
Umr Jansen
6912 POSTS0 COMMENTS