The if...else statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement in the optional else clause will be executed.

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 viewBox attribute defines the position and dimension, in user space, of an SVG viewport.

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.

A literal character specifies exactly itself to be matched in the input text.

The max attribute specifies the maximum value of the active animation duration.

The requiredFeatures attribute takes a list of feature strings, with the individual strings separated by white space. It determines whether or not all of the named features are supported by the browser; if all of them are supported, the attribute evaluates to true end the element is rendered; otherwise, the attribute evaluates to false and the current element and its children are skipped and thus will not be rendered. This provides a way to design SVG that gracefully falls back when features aren't available.

The vert-origin-y attribute indicates the y-coordinate in the font coordinate system of the origin of a glyph to be used when drawing vertically oriented text.

The class declaration creates a binding of a new class to a given name.

The repeatDur attribute specifies the total duration for repeating an animation.