How to get array structure with alert() in JavaScript?

Last Updated : 06 Sep, 2019

Here is the code to see the array structure using alert() . Here below few techniques
are discussed
Approach 1:

First take the values in a variable(lets arr).
Pass the array name in the alert() .
We can directly use the array name because arrayName automatically converted to arrayName.toString()

Example 1: This example follows the approach discussed above.

<!DOCTYPE HTML> 
<html> 
  
<head> 
    <title> 
        How to get array structure  
        with alert() in JavaScript? 
    </title> 
</head> 
  
<body style="text-align:center;" id="body"> 
    <h1 style="color:green;">  
            GeeksForGeeks  
    </h1> 
    
    <p id="GFG_UP" style="font-size: 15px; font-weight: bold;"> 
    </p> 
    
    <button onclick="gfg_Run()"> 
        Click here 
    </button> 
    
    <script> 
        var el_up = document.getElementById("GFG_UP"); 
        var arr = [1, 2, 4, 6, 9]; 
        el_up.innerHTML =  
"Click on the button to see the array structure using Alert().<br> Array is = " 
        + arr; 
  
        function gfg_Run() { 
            alert(arr); 
        } 
    </script> 
</body> 
  
</html> 

Output:

Before clicking on the button:
After clicking on the button:

Approach 2:

First take the values in a variable(lets arr).
Pass the array name in the alert() .
We can use .join() method for our simplicity to see the array elements each in a line.

Example 2: This example follows the approach discussed above.

<!DOCTYPE HTML> 
<html> 
  
<head> 
    <title> 
        How to get array structure 
        with alert() in JavaScript? 
    </title> 
</head> 
  
<body style="text-align:center;" id="body"> 
    <h1 style="color:green;">  
            GeeksForGeeks  
        </h1> 
    <p id="GFG_UP" style="font-size: 15px; font-weight: bold;"> 
    </p> 
    <button onclick="gfg_Run()"> 
        Click here 
    </button> 
    <script> 
        var el_up = document.getElementById("GFG_UP"); 
        var arr = [1, 2, 4, 6, 9]; 
        el_up.innerHTML =  
"Click on the button to see the array structure using Alert().<br> Array is = " 
        + arr; 
  
        function gfg_Run() { 
            alert(arr.join('\n')); 
        } 
    </script> 
</body> 
  
</html> 