In this article, we will learn what is the Uncaught SyntaxError: Unexpected identifier error and discuss causes and solutions of it.
What is an Unexpected Identifier Error?
The Uncaught SyntaxError: Unexpected identifier error is a syntax error that occurs when the computer’s parser cannot recognize a particular token, or identifier, as a valid one in the programming language.
For example, when a programmer has mistyped a keyword, function name, or variable name. It can also occur if the programmer has inadvertently created a new token that the computer does not recognize.
When the computer encounters the Uncaught SyntaxError: Unexpected identifier error, it will usually throw an error message that tells the programmer which line in the code has the problem. This error message can help the programmer locate and fix the problem quickly.
What Causes Unexpected Identifier Errors?
There are many common reasons that can cause the Uncaught SyntaxError: Unexpected identifier error.
1. The most common cause is a typo in a keyword, function name, or variable name.
// ❌ Uncaught SyntaxError: Unexpected identifier
Let name = 'Jane'; // 👈️ should be let
// ❌ Uncaught SyntaxError: Unexpected identifier
Class Book { // 👈️ should be class
}
// ❌ Uncaught SyntaxError: Unexpected identifier
Function sum(a,b) { // 👈️ should be function
return a + b;
}As you can see in the above example how misspelling a keyword causes the error. Because keywords are case-sensitive.
2. Another common cause is forgetting to include a colon, comma, bracket, parenthesis, or quote.
// ❌ Uncaught SyntaxError: Unexpected identifier
const user = {
firstName: 'Jane' // 👈️ missing comma
lastName: 'Doe',
};
//👇 missing quote
const userName = 'Jane 3. The error also occurs when you add an extra colon, comma, bracket, parenthesis, or quote.
// ❌ Uncaught SyntaxError: Unexpected identifier
const user = {
firstName: 'Jane',, // 👈️ added extra comma
lastName: 'Doe',
};
//👇 added extra quote
const userName = 'Jane'' How to Solve Unexpected Identifier Errors?
To solve Uncaught SyntaxError: Unexpected identifier is to paste your code into an online Syntax Validator. The validator should be able to tell you on which line the error occurs. You can hover over the red squiggly line to see additional details.
Alternately, you can use the browser’s console tab to check where the error occurred.
If you want to prevent such SyntaxError errors, use IDE or code editor such as VS code, sublime, Atom etc.
Conclusion
The Unexpected Identifier errors are a common issue for JavaScript developers, but they can be easily solved with syntax validators. Also, it can be prevented using IDE or code editors.
Learn More:
- Dynamically Access Object Property Using Variable in JavaScript
- Check if a Key exists in an Object in JavaScript
- Replace All String Occurrences in JavaScript
- Get the Last N Elements of an Array in JavaScript
- Calculate Percentage Between Two Numbers in JavaScript
- Remove Special Characters from a String in JavaScript
- Using async/await with a forEach loop
- Wait for all promises to resolve in JavaScript
