JavaScript errors may arise when the browser has difficulty executing JavaScript code. JavaScript is a programming language used extensively for creating interactive and dynamic web pages. Typically, when a JavaScript error happens, an error message is shown in the console or as a pop-up window, depending on the script’s execution.
Syntax errors, logical errors, or problems with how the code communicates with other parts of the web page or external resources such as APIs or databases can all lead to JavaScript errors. Several common JavaScript error messages include “SyntaxError,” “ReferenceError,” “TypeError,” and “RangeError.”
There are several types of JavaScript errors that can occur when executing JavaScript code in a web page or application. Here are some of the most common types of JavaScript errors:
| Error Type | Description |
|---|---|
| SyntaxError | Occurs when the code contains a syntax error, such as a missing or misplaced bracket, parenthesis, or semicolon. |
| ReferenceError | Occurs when the code attempts to access a variable or function that doesn’t exist or is out of scope. |
| TypeError | Occurs when the code attempts to use a value that is of the wrong type, such as passing a string to a function that expects a number. |
| RangeError | Occurs when the code attempts to use a value that is outside of the range of acceptable values, such as using a negative index value to access an array. |
| NetworkError | Occurs when there is a problem with the network connection, such as when the browser can’t reach the server or there is a timeout while waiting for a response. |
| InternalError | Occurs when there is an internal error in the JavaScript engine or runtime, such as a stack overflow or out-of-memory error. |
JavaScript Error Example
Simple example code of a TypeError in JavaScript:
<!DOCTYPE html>
<html>
<body>
<script>
let num = 15;
console.log(num.split(""));
</script>
</body>
</html>Output:
Syntax error
const func = () =>
console.log(hello)
}Reference Error
console.log(x);Evaluation Error
try{
throw new EvalError("'Throws an error'")
}catch(error){
console.log(error.name, error.message)
}RangeError
const checkRange = (num)=>{
if (num < 30) throw new RangeError("Wrong number");
return true
}
checkRange(20);Internal Error
switch(condition) {
case 1:
...
break
case 2:
...
break
case 3:
...
break
case 4:
...
break
case 5:
...
break
case 6:
...
break
case 7:
...
break
... up to 500 cases
}Use try…catch…finally Statement to handle errors in JavaScript.
When you come across a JavaScript error, it’s crucial to review the error message carefully and attempt to determine the underlying cause. This usually requires examining the code to identify syntax errors or logical issues and verifying that any external resources the code relies on are working properly.
Comment if you have any doubts or suggestions on this JS Error topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version