The JavaScript exception "Iterator constructor can't be used directly" or "AsyncIterator constructor can't be used directly" occurs when you try to use the Iterator() or AsyncIterator() constructors directly to create instances. These constructors are abstract classes and should only be inherited from.

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The JavaScript exception "identifier starts immediately after numeric literal" occurs when an identifier started with a digit. Identifiers can only start with a letter, underscore (_), or dollar sign ($).

A wildcard matches all characters except line terminators. It also matches line terminators if the s flag is set.

The JavaScript strict mode-only exception "applying the 'delete' operator to an unqualified name is deprecated" occurs when variables are attempted to be deleted using the delete operator.

The JavaScript exception "reference to undeclared private field or method #x" occurs when a private name is used, but this private name is not declared in the class scope.

The JavaScript exception "return not in function" occurs when a return statement is called outside of a function.

The z attribute defines the location along the z-axis for a light source in the coordinate system established by the primitiveUnits attribute on the <filter> element, assuming that, in the initial coordinate system, the positive z-axis comes out towards the person viewing the content and assuming that one unit along the z-axis equals one unit in x and y.

The JavaScript exception "can't delete non-configurable array element" occurs when it was attempted to shorten the length of an array, but one of the array's elements is non-configurable.