How to Fix a Reserved Word SyntaxError in JavaScript

Fix the error by finding the reported word in the role of a variable, parameter, function, class, or other binding, then rename it to an ordinary identifier. For example, change const enum = { RED: 0 }; to const colorEnum = { RED: 0 };. If renaming does not resolve the parse error, check the surrounding syntax and whether the code is a module, strict-mode script, async function, or generator.

What “Unexpected reserved word” means

JavaScript reports this as a syntax error when parsing encounters a word in a grammatical position where that word is not allowed. A common cause is using a reserved word as a binding name. The ECMAScript specification defines it this way: “A reserved word is an IdentifierName that cannot be used as an identifier.” (ECMAScript 2026 specification.)

Engines phrase the error differently. V8 may report SyntaxError: Unexpected reserved word; Firefox and Safari may name a reserved identifier or say that a word cannot be used as a variable name. The wording varies, but the useful clue is the token and its location. (MDN: reserved identifier error.)

Fix it step by step

1. Read the full message. Note the file, line, column, and token the parser reports. The highlighted token is a lead; sometimes an earlier typo is what made the parser lose track of the syntax.
2. Inspect the token’s role. Determine whether it names a binding, such as a variable or function parameter, or is used as an object property name. The same spelling can be invalid as a binding and valid as a property name.
3. Check the context. Establish whether the code is a module, strict-mode script, async function, or generator. Some names are restricted only in particular contexts.
4. Rename an invalid binding. Choose a descriptive identifier that is allowed in that context, such as colorEnum instead of enum.
5. Parse or run the code again. If the error remains, inspect the new reported location, nearby punctuation, and any transpiler or parser configuration.

Runnable examples

Invalid binding and corrected version

// Invalid: `enum` is not a valid binding name.
const enum = { RED: 0 };

// Corrected: use an ordinary identifier.
const colorEnum = { RED: 0 };
console.log(colorEnum.RED);

Save the corrected code as reserved-word.js and run it with Node.js using node reserved-word.js. The invalid line will fail during parsing, before the program runs; remove or comment it out to run the corrected example.

Property name versus binding name

// A reserved spelling can be used as an object property name.
const settings = { class: "compact" };
console.log(settings.class);

// A computed property also makes the property role explicit.
const options = { ["await"]: true };
console.log(options["await"]);

Property access and object property names follow different grammar rules from variable declarations. Do not rename a property automatically just because its spelling appears in an error; first verify whether it is actually being parsed as a binding.

Contextual restrictions: await and yield

// In module code, `await` is reserved for top-level await.
// Rename a binding that would otherwise use that name:
const waitForResult = Promise.resolve("done");

// In a generator, `yield` is an expression keyword:
function* values() {
  yield 1;
}

console.log([...values()]);

Module code and async function bodies restrict await; generator bodies and strict mode restrict yield. A name that parses in one context can fail in another. (MDN: lexical grammar and reserved words.)

Which words and contexts to check

Many language keywords cannot be used as bindings, including class, const, function, return, and var. Other cases depend on grammar context:

Word or group	Context to inspect	Typical response
await	Module code and async function bodies	Rename a binding, or use await only as the intended expression.
yield	Strict mode and generator bodies	Rename a binding; use yield as a generator expression where appropriate.
let	Declaration positions and strict mode	Check whether the parser reads it as a declaration; choose another binding name if needed.
implements, interface, package, private, protected, public, static	Strict-mode code	Use a different binding name.
class, const, function, return, var	Binding positions	Use a descriptive non-keyword identifier.

The exact grammar rules depend on the token’s position; consult MDN’s reserved-word reference and the ECMAScript specification for a particular case.

Why changing strict mode is usually the wrong fix

Do not disable strict mode as the routine remedy. It can change program semantics, and it does not make generally reserved keywords available as binding names. Renaming the invalid binding addresses the cause and works across execution contexts. Also remember that modules are strict by default, so code moved from a classic script into a module can expose a name restriction.

Troubleshooting

Symptom	Likely cause	What to do
The parser points at a familiar word such as await or yield.	The word is used as a binding in a context that reserves it.	Check whether the file is a module, async function, or generator, then rename the binding.
The same word works in an object but fails in a declaration.	Property names and bindings have different grammar rules.	Inspect its syntactic role; keep a valid property name and rename only an invalid binding.
The reported location seems unrelated.	A missing delimiter, earlier typo, or malformed construct may have shifted parsing.	Check the preceding lines for unmatched braces, parentheses, quotes, commas, or incomplete declarations.
The error appears only after enabling modules or strict mode.	The new execution context restricts additional names.	Rename the binding and verify the intended module or script configuration.
An escaped identifier still fails.	JavaScript checks an identifier’s decoded value; escaping does not turn a reserved word into an allowed binding.	Choose a different identifier instead of spelling the reserved word with escapes. (MDN lexical grammar.)
The message changes after fixing one token.	Parsing progressed and found another invalid token or syntax problem.	Address the new location and repeat the role-and-context check.
The error is shown in generated or bundled code.	A source transform, build output, or parser target may be involved.	Inspect the source map and original source, then check the tool’s module mode and language target.

Performance, reliability, and cost

This is a parse-time issue, so fixing the binding does not require a runtime optimization or paid tool. Renaming a binding has negligible performance impact in ordinary application code. Preserve the program’s intended behavior when changing identifiers: update references consistently, and use your editor’s rename-symbol feature when available.

For reliability, make the smallest syntax correction, then parse or run the file in the same mode used by the application. If the project has a build step, check both the source and generated output. This catches context differences such as script versus module parsing without masking the underlying problem.

Or skip the browser setup

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curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webp

import requests
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open("shot.webp", "wb").write(r.content)

const q = new URLSearchParams({ access_key: 'YOUR_API_KEY', url: 'https://stripe.com' });
const res = await fetch(`https://api.screenshotneo.com/v1/shot?${q}`);

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FAQ

Does the error mean JavaScript cannot parse the whole file?

Yes. A syntax error prevents execution of that parsed unit until the invalid syntax is corrected.

Can I use a reserved word as an object key?

Often, yes. Object property names and identifier bindings have different rules; check the exact grammar position.

Why does another browser show a different error?

JavaScript engines use different diagnostic wording and may point to different locations. Diagnose the token, its role, and its context.

Do backslashes let me use a reserved word as a variable name?

No. Identifier escapes are interpreted before reserved-word checks, so an escaped spelling that decodes to a reserved word remains reserved.