wp-includes/rest-api.php:1520Determines if a given value is boolean-like.
$maybe_boolbool|stringboolfunction rest_is_boolean( $maybe_bool ) { if ( is_bool( $maybe_bool ) ) { return true; } if ( is_string( $maybe_bool ) ) { $maybe_bool = strtolower( $maybe_bool ); $valid_boolean_values = array( 'false', 'true', '0', '1', ); return in_array( $maybe_bool, $valid_boolean_values, true ); } if ( is_int( $maybe_bool ) ) { return in_array( $maybe_bool, array( 0, 1 ), true ); } return false;}Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.