The const declaration declares block-scoped local variables. The value of a constant can't be changed through reassignment using the assignment operator, but if a constant is an object, its properties can be added, updated, or removed.

The null value represents the intentional absence of any object value. It is one of JavaScript's primitive values and is treated as falsy for boolean operations.

The font-stretch attribute indicates the desired amount of condensing or expansion in the glyphs used to render the text.

The clipPathUnits attribute indicates which coordinate system to use for the contents of the <clipPath> element.

The try...catch statement is comprised of a try block and either a catch block, a finally block, or both. The code in the try block is executed first, and if it throws an exception, the code in the catch block will be executed. The code in the finally block will always be executed before control flow exits the entire construct.

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

A block statement is used to group zero or more statements. The block is delimited by a pair of braces ("curly braces") and contains a list of zero or more statements and declarations.

The dur attribute indicates the simple duration of an animation.

The descent attribute defines the maximum unaccented depth of the font.

The typeof operator returns a string indicating the type of the operand's value.