In ECMAScript there are five simple data types (also called primitive types) and one complex data type.

Those data types are listed in table below.

The list of JavaScript data types

the undefined type A data type assigned to variables that have been declared with var operator but the type hasn't been assigned yet.
the null type The null data type is an empty object pointer. It is often used to declare an object or to reset an existing one.
the Boolean type The Boolean data type is used to test flow controlling conditions inside a code. The values may be TRUE or FALSE.
the number type This type is used to address JavaScript numbers. The numbers in JavaScript may be expressed as integers or floating-points (decimal point).
the string type The string type represents all data that are made of characters defined within UTF-16 standard and delimited with single quotes ('') or double quotes ("").
the object type The object data type is a complex data type and the key to JavaScript functionality. Almost everything inside JS is considered to be an object, including functions and arrays.