Submitted by gwagner on
The four types of basic data structures supported by JavaScript are: array lists, maps, records and JSON tables. The following list provides a summary:
-
Array lists, such as
["one","two","three"], are special JS objects called 'arrays', but since they are dynamic, they are rather array lists as defined in the Java programming language. -
Maps are also special JS objects, such as
{"one":1,"two":2,"three":3}, as discussed below. -
Records, such as
{firstName:"Tom",lastName:"Smith"}, are also special JS objects, as discussed below. -
JSON tables are special maps where the values are records representing entities (with a primary key slot), and the keys are the primary keys of these entity records (for an example of such a table, see Storing database tables in JavaScript's Local Storage).
Notice that our distinction between maps, records and JSON tables is a
purely conceptual distinction, and not a syntactical one. For a JavaScript
engine, both {firstName:"Tom",lastName:"Smith"} and
{"one":1,"two":2,"three":3} are just objects. But conceptually,
{firstName:"Tom",lastName:"Smith"} is a record because
firstName and lastName are intended to denote
properties or fields, while {"one":1,"two":2,"three":3} is a
map because "one", "two" and
"three" are not intended to denote properties/fields, but are
just arbitrary string values used as keys in a map.
Making such conceptual distinctions helps to better understand the options offered by JavaScript.
