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 let declaration declares re-assignable, block-scoped local variables, optionally initializing each to a value.

The end attribute defines an end value for the animation that can constrain the active duration.

The <feColorMatrix> SVG filter element changes colors based on a transformation matrix. Every pixel's color value [R,G,B,A] is matrix multiplied by a 5 by 5 color matrix to create new color [R',G',B',A'].

The encodeURIComponent() function encodes a URI by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character (will only be four escape sequences for characters composed of two surrogate characters). Compared to encodeURI(), this function encodes more characters, including those that are part of the URI syntax.

The <feComposite> SVG filter primitive performs the combination of two input images pixel-wise in image space using one of the Porter-Duff compositing operations: over, in, atop, out, xor, lighter, or arithmetic.

The async function* keywords can be used to define an async generator function inside an expression.

The RegExp object is used for matching text with a pattern.

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

The do...while statement creates a loop that executes a specified statement until the test condition evaluates to false. The condition is evaluated after executing the statement, resulting in the specified statement executing at least once.