Programming languages all have built-in data structures, but these often differ from one language to another. This article attempts to list the built-in data structures available in JavaScript and what properties they have. These can be used to build other data structures. Wherever possible, comparisons with other languages are drawn.
JavaScript is a loosely typed and dynamic language. Variables in JavaScript are not directly associated with any particular value type, and any variable can be assigned (and re-assigned) values of all types:
let foo = 42;
foo = 'bar';
foo = true;