The less than or equal (<=) operator returns true if the left operand is less than or equal to the right operand, and false otherwise.

The <feMerge> SVG element allows filter effects to be applied concurrently instead of sequentially. This is achieved by other filters storing their output via the result attribute and then accessing it in a <feMergeNode> child.

The <feFuncR> SVG filter primitive defines the transfer function for the red component of the input graphic of its parent <feComponentTransfer> element.

The DataView view provides a low-level interface for reading and writing multiple number types in a binary ArrayBuffer, without having to care about the platform's endianness.

The <polygon> SVG element defines a closed shape consisting of a set of connected straight line segments. The last point is connected to the first point.

The <symbol> SVG element is used to define graphical template objects which can be instantiated by a <use> element.

The JavaScript exception "super() called twice in derived class constructor" occurs when the super() is called a second time for a given derived class constructor.

The JavaScript exception "repeat count must be non-negative" occurs when the String.prototype.repeat() method is used with a count argument that is a negative number.

The [Symbol.iterator]() method of arguments objects implements the iterable protocol and allows arguments objects to be consumed by most syntaxes expecting iterables, such as the spread syntax and for...of loops. It returns an array iterator object that yields the value of each index in the arguments object.

The JavaScript exception "new keyword cannot be used with an optional chain" occurs when the constructor of a new expression is an optional chain, or if there's an optional chain between the constructor and the parenthesized list of arguments.