The <feSpecularLighting> SVG filter primitive lights a source graphic using the alpha channel as a bump map. The resulting image is an RGBA image based on the light color. The lighting calculation follows the standard specular component of the Phong lighting model. The resulting image depends on the light color, light position and surface geometry of the input bump map. The result of the lighting calculation is added. The filter primitive assumes that the viewer is at infinity in the z direction.

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

The addition (+) operator produces the sum of numeric operands or string concatenation.

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 <mask> SVG element defines an alpha mask for compositing the current object into the background. A mask is used/referenced using the mask property.

The void operator evaluates the given expression and then returns undefined.

The <title> SVG element provides an accessible, short-text description of any SVG container element or graphics element.

The dx attribute indicates a shift along the x-axis on the position of an element or its content.

The fill attribute has two different meanings. For shapes and text it's a presentation attribute that defines the color (or any SVG paint servers like gradients or patterns) used to paint the element; for animation it defines the final state of the animation.

The isNaN() function determines whether a value is NaN, first converting the value to a number if necessary. Because coercion inside the isNaN() function can be surprising, you may prefer to use Number.isNaN().