How to duplicate elements of an array in the same array with JavaScript?


Following is the code to duplicate elements of an array in the same array −

Example

 Live Demo

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" >
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .result,.sample {
      font-size: 18px;
      font-weight: 500;
      color: rebeccapurple;
   }
   .result {
      color: red;
   }
</style>
</head>
<body>
<h1>Duplicate elements of an array in the same array</h1>
<div class="sample">[1,2,3,4,'A']</div>
<div class="result"></div>
<button class="Btn">CLICK HERE</button>
<h3>Click on the above button to duplicate the elements of the above array</h3>
<script>
   let resEle = document.querySelector(".result");
   let BtnEle = document.querySelector(".Btn");
   let arr = [1, 2, 3, 4, "A"];
      BtnEle.addEventListener("click", () => {
         arr = arr.concat(arr).sort();
         resEle.innerHTML = arr;
      });
</script>
</body>
</html>

Output

The above code will produce the following output −

On clicking the ‘CLICK HERE’ button −


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