The JavaScript exception "character class escape cannot be used in class range in regular expression" occurs when a Unicode-aware regular expression pattern contains a character class where a boundary of a character range is another character class, such as a character class escape.

A non-capturing group groups a subpattern, allowing you to apply a quantifier to the entire group or use disjunctions within it. It acts like the grouping operator in JavaScript expressions, and unlike capturing groups, it does not memorize the matched text, allowing for better performance and avoiding confusion when the pattern also contains useful capturing groups.

The rotate attribute specifies how the animated element rotates as it travels along a path specified in an <animateMotion> element.

The u1 attribute specifies list of Unicode characters (refer to the description of the unicode attribute of the <glyph> element for a description of how to express individual Unicode characters) and/or ranges of Unicode characters, which identify a set of possible first glyph in a kerning pair.

The <path> SVG element is the generic element to define a shape. All the basic shapes can be created with a path element.

Generally speaking, a function is a "subprogram" that can be called by code external (or internal, in the case of recursion) to the function. Like the program itself, a function is composed of a sequence of statements called the function body. Values can be passed to a function as parameters, and the function will return a value.

The k2 attribute defines one of the values to be used within the arithmetic operation of the <feComposite> filter primitive.

The operator attribute has two meanings based on the context it's used in. Either it defines the compositing or morphing operation to be performed.

The pointsAtX attribute represents the x location in the coordinate system established by attribute primitiveUnits on the <filter> element of the point at which the light source is pointing.

The JavaScript exception "repeat count must be less than infinity" occurs when the String.prototype.repeat() method is used with a count argument that is infinity.