Custom Errors in JavaScript

JavascriptWeb DevelopmentObject Oriented Programming

Following is the code to implement custom errors in JavaScript −

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 {
      font-size: 18px;
      font-weight: 500;
      color: rebeccapurple;
   }
</style>
</head>
<body>
<h1>Custom Errors in JavaScript</h1>
<div class="result"></div>
<button class="Btn">CLICK HERE</button>
<h3>
Click on the above button to create a custom error and display it
</h3>
<script>
   let resEle = document.querySelector(".result");
   let sampleEle = document.querySelector(".sample");
   let BtnEle = document.querySelector(".Btn");
   class CustomError extends Error {
      constructor(message) {
         super(message);
         this.name = "CustomError";
      }
   }
   function test() {
      throw new CustomError("New Error thrown");
   }
   BtnEle.addEventListener("click", () => {
      try {
         test();
      }
      catch (err) {
         resEle.innerHTML += "err.name = " + err.name + "<br>";
         resEle.innerHTML += "err.message = " + err.message + "<br>";
      }
   });
</script>
</body>
</html>

Output

The above code will produce the following output −

On clicking the ‘CLICK HERE’ button −

raja
Published on 17-Jul-2020 08:31:52
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