The eval() function evaluates JavaScript code represented as a string and returns its completion value. The source is parsed as a script.

The Set object lets you store unique values of any type, whether primitive values or object references.

The decoding attribute, valid on <image> elements, provides a hint to the browser as to whether it should perform image decoding along with rendering other content in a single presentation step that looks more "correct" (sync), or render and present the other content first and then decode the image and present it later (async). In practice, async means that the next paint does not wait for the image to decode.

The Reflect namespace object contains static methods for invoking interceptable JavaScript object internal methods. The methods are the same as those of proxy handlers.

The font-variant attribute indicates whether the text is to be rendered using variations of the font's glyphs.

The bitwise AND assignment (&=) operator performs bitwise AND on the two operands and assigns the result to the left operand.

The multiplication assignment (*=) operator performs multiplication on the two operands and assigns the result to the left operand.

The new operator lets developers create an instance of a user-defined object type or of one of the built-in object types that has a constructor function.

The elevation attribute specifies the direction angle for the light source from the XY plane towards the Z-axis, in degrees. Note that the positive Z-axis points towards the viewer of the content.

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