← back to v133 · error-iserror
conformance · v133
v133 · error-iserror — conformance probe
7 assertions drawn from the spec. Each is a single contract the spec text makes. Pass/fail reflects what this browser executed; blocked means the contract was not run because it needs user mediation, hardware, or another unavailable precondition. Open the page in Chrome stable / canary / Firefox / Safari to compare.
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pass
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fail
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7
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| id | contract | kind | verdict | detail |
|---|---|---|---|---|
error-iserror-exists |
Error.isError is exposed as a static method on the Error constructor. spec ↗ | exists | … | |
error-iserror-is-function |
Error.isError is callable. | typeof | … | |
error-iserror-true-for-error |
Error.isError(new Error()) returns true. spec ↗ | script | … | |
error-iserror-true-for-typeerror |
Error.isError returns true for subclass instances such as TypeError. | script | … | |
error-iserror-false-for-error-like |
Error.isError returns false for plain objects with name/message that merely duck-type as errors. | script | … | |
error-iserror-false-for-non-error |
Error.isError returns false for primitive values such as strings and numbers. | script | … | |
error-iserror-cross-realm |
Error.isError identifies Error instances from another realm (cross-realm iframe), where instanceof would fail. | script | … |