There are several basic shapes used for most SVG drawing. The purpose of these shapes is fairly obvious from their names. Some of the parameters that determine their position and size are given, but an element reference would probably contain more accurate and complete descriptions along with other properties that won't be covered in here. However, since they're used in most SVG documents, it's necessary to give them some sort of introduction.

The JavaScript exception "missing = in const declaration" occurs when a const declaration was not given a value in the same statement (like const RED_FLAG;). You need to provide one (const RED_FLAG = "#ff0").

The image-rendering attribute provides a hint to the browser about how to make speed vs. quality tradeoffs as it performs image processing.

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.

This page lists features of JavaScript that are deprecated (that is, still available but planned for removal) and obsolete (that is, no longer usable).

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

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

The JavaScript exception "is not a constructor" occurs when there was an attempt to use an object or a variable as a constructor, but that object or variable is not a constructor.

The JavaScript exception "can't set prototype of this object" occurs when attempting to set the prototype of an object, but the object's prototype is frozen, either by being a built-in immutable prototype object, or by being non-extensible.

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.