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function expression

The function declaration creates a binding of a new function to a given name.

Functions reference

The name of a formal parameter for the function. Maximum number of arguments varies in different engines. For the parameters' syntax, see the Functions reference.

Block-level function declaration

Warning: In non-strict mode, function declarations inside blocks behave strangely. Only declare functions in blocks if you are in strict mode.

Block-level function declaration

Warning: In non-strict mode, function declarations inside blocks behave strangely. Only declare functions in blocks if you are in strict mode.

Block-level function declaration

Warning: In non-strict mode, function declarations inside blocks behave strangely. Only declare functions in blocks if you are in strict mode.

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This page was last modified on Jul 8, 2025 by MDN contributors.

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