The marker-end attribute defines the arrowhead or polymarker that will be drawn at the final vertex of the given shape.

A character escape represents a character that may not be able to be conveniently represented in its literal form.

The JavaScript exception "import declarations may only appear at top level of a module" occurs when an import declaration is not at the top level of a module. This might be because the import declaration is nested in other constructs (functions, blocks, etc.), or more often because the current file is not treated as a module.

The primitiveUnits attribute specifies the coordinate system for the various length values within the filter primitives and for the attributes that define the filter primitive subregion.

The JavaScript exception "too much recursion" or "Maximum call stack size exceeded" occurs when there are too many function calls, or a function is missing a base case.

The min attribute specifies the minimum value of the active animation duration.

The switch statement evaluates an expression, matching the expression's value against a series of case clauses, and executes statements after the first case clause with a matching value, until a break statement is encountered. The default clause of a switch statement will be jumped to if no case matches the expression's value.

The opacity attribute specifies the transparency of an object or of a group of objects, that is, the degree to which the background behind the element is overlaid.

Classes are a template for creating objects. They encapsulate data with code to work on that data. Classes in JS are built on prototypes but also have some syntax and semantics that are unique to classes.

The JavaScript strict mode-only exception "is read-only" occurs when a global variable or object property that was assigned to is a read-only property.