The in operator returns true if the specified property is in the specified object or its prototype chain.

JavaScript supports a compact set of statements, specifically control flow statements, that you can use to incorporate a great deal of interactivity in your application. This chapter provides an overview of these statements.

The <feMorphology> SVG filter primitive is used to erode or dilate the input image. Its usefulness lies especially in fattening or thinning effects.

The isFinite() function determines whether a value is finite, first converting the value to a number if necessary. A finite number is one that's not NaN or ±Infinity. Because coercion inside the isFinite() function can be surprising, you may prefer to use Number.isFinite().

The <feDistantLight> filter primitive defines a distant light source that can be used within a lighting filter primitive: <feDiffuseLighting> or <feSpecularLighting>.

The <metadata> SVG element adds metadata to SVG content. Metadata is structured information about data. The contents of <metadata> should be elements from other XML namespaces such as RDF, FOAF, etc.

The SVG <animateMotion> element provides a way to define how an element moves along a motion path.

The conditional (ternary) operator is the only JavaScript operator that takes three operands: a condition followed by a question mark (?), then an expression to execute if the condition is truthy followed by a colon (:), and finally the expression to execute if the condition is falsy. This operator is frequently used as an alternative to an if...else statement.

The <feDiffuseLighting> SVG filter primitive lights an image using the alpha channel as a bump map. The resulting image, which is an RGBA opaque image, depends on the light color, light position and surface geometry of the input bump map.

The JavaScript exception "duplicate capture group name in regular expression" occurs when a regular expression pattern contains two or more named capturing groups with the same name, and these capture groups could be matched at the same time.