Operators from the C and JavaScript lineage, each built by doubling or combining a character that means something else on its own. That construction is the group's defining property and its main hazard: one equals sign assigns, two compare with type conversion, three compare without, and miscounting strokes is among the most common mistakes made by people new to the language. Where ECMA-262 defines the behaviour it is cited; where a form is shared across languages that treat it differently, the record says which language it describes.
An equals sign and angle bracket introducing a compact function.
Three horizontal strokes comparing value and type together.
A question mark and colon choosing between two values.
Two question marks supplying a fallback for an absent value.
A question mark and dot stopping a lookup on an absent value.
Three dots unpacking a collection into its elements.
Two plus signs raising a value by one.
Two minus signs lowering a value by one.
Two stacked colons reaching inside a namespace or class.
Two forward slashes making the rest of a line a comment.