The new.target meta-property lets you detect whether a function or constructor was called using the new operator. In constructors and functions invoked using the new operator, new.target returns a reference to the constructor or function that new was called upon. In normal function calls, new.target is undefined.

The stroke-opacity attribute is a presentation attribute defining the opacity of the paint server (color, gradient, pattern, etc.) applied to the stroke of a shape.

The import attributes feature instructs the runtime about how a module should be loaded, including the behavior of module resolution, fetching, parsing, and evaluation. It's supported in import declarations, export...from declarations, and dynamic import().

The tableValues attribute defines a list of numbers defining a lookup table of values for a color component transfer function.

The lang attribute specifies the primary language used in contents and attributes containing text content of particular elements.

The JavaScript exception "await is only valid in async functions, async generators and modules" occurs when an await expression is used outside of async functions or modules or other async contexts.

The optional chaining (?.) operator accesses an object's property or calls a function. If the object accessed or function called using this operator is undefined or null, the expression short circuits and evaluates to undefined instead of throwing an error.

The JavaScript exception "x is (not) y" occurs when there was an unexpected type. Oftentimes, unexpected undefined or null values.

The mode attribute defines the blending mode on the <feBlend> filter primitive.

The JavaScript exception "invalid unicode escape in regular expression" occurs when the \c and \u character escapes are not followed by valid characters.