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JavaScript Error message Property

Javascript Web Development Object Oriented Programming

The message property of JavaScript Error objects contains a human-readable description of the error. It's automatically set when an error occurs and can also be customized when creating custom errors.

Syntax

error.message

Example: Accessing Error Message

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>JavaScript Error message Property</title>
<style>
    body {
        font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
    }
    .sample {
        font-size: 18px;
        font-weight: 500;
        color: #d32f2f;
        margin: 10px 0;
    }
    .btn {
        padding: 10px 20px;
        font-size: 16px;
        background-color: #1976d2;
        color: white;
        border: none;
        cursor: pointer;
        border-radius: 4px;
    }
</style>
</head>
<body>


<button class="btn">CLICK HERE</button>
<h3>Click the button to see the error message</h3>

<script>
    let sampleEle = document.querySelector(".sample");
    document.querySelector(".btn").addEventListener("click", () => {
        try {
            // Intentional typo: confrm instead of confirm
            confrm('Are you sure');
        } catch (e) {
            sampleEle.innerHTML = "Error: " + e.message;
        }
    });
</script>
</body>
</html>

Creating Custom Error Messages

<!DOCTYPE html>
<html>
<head>
<title>Custom Error Messages</title>
</head>
<body>


<script>
    function validateAge(age) {
        if (age < 0) {
            throw new Error("Age cannot be negative");
        }
        if (age > 150) {
            throw new Error("Age seems unrealistic");
        }
        return "Valid age: " + age;
    }

    let output = document.getElementById("output");
    
    try {
        console.log(validateAge(-5));
    } catch (error) {
        output.innerHTML += "<p>Error: " + error.message + "</p>";
    }
    
    try {
        console.log(validateAge(200));
    } catch (error) {
        output.innerHTML += "<p>Error: " + error.message + "</p>";
    }
</script>
</body>
</html>

Common Error Types and Messages

Error Type	Example Message	Cause
ReferenceError	"variable is not defined"	Using undefined variables
TypeError	"Cannot read property 'x' of null"	Accessing properties on null/undefined
SyntaxError	"Unexpected token"	Invalid JavaScript syntax
Custom Error	Your custom message	Thrown with new Error()

Key Points

The message property is read/write - you can modify it after creating an error
Different browsers may format error messages slightly differently
Custom error messages should be descriptive and user-friendly
The message property doesn't include the error type - use error.name for that

Conclusion

The message property provides essential error information for debugging and user feedback. Use it in try-catch blocks to handle errors gracefully and create meaningful custom error messages.

AmitDiwan

Updated on: 2026-03-15T23:18:59+05:30

271 Views

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