Error.isError()
The Error.isError() static method determines whether the passed value is an Error.
Browser support
| Feature | Desktop | Mobile | ||||
|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Safari | Chrome Android | Safari iOS | |
| 134 | 134 | 138 | 18.4 | 134 | 18.4 | |
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)
Notes 2 item(s)
Limitation
- This browser only partially implements this feature
Implementation note
- Returns `false` for `DOMException` instances.
Notes 2 item(s)
Limitation
- This browser only partially implements this feature
Implementation note
- Returns `false` for `DOMException` instances.
Syntax
JAVASCRIPT
Error.isError(new Error('test')); // true
Error.isError(new TypeError()); // true
Error.isError({ message: 'fake' }); // falseLive demo
Check native Error objects
Use Error.isError when available, otherwise fall back to instanceof Error.
JavaScript
Output
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Inspect different thrown values
Compare errors, strings, and plain objects with the same helper.
JavaScript
Output
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Use inside catch handling
Normalize catch blocks that may receive non-Error values.
JavaScript
Output
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Use cases
-
Shared error pipelines
Normalize error handling in utilities that may receive thrown values from different execution contexts.
-
Runtime guards
Distinguish real Error objects from arbitrary thrown values before formatting or reporting them.
Cautions
- A reliable error check still does not guarantee the value contains the information your UI needs.
- Thrown strings and custom objects remain possible, so keep fallback handling in place.
Accessibility
- Reliable error detection helps ensure users receive consistent failure messages and recovery options.
- Error handling only improves accessibility if the resulting UI feedback is perceivable and actionable.