| Class | Description |
| ArgError | Arguments error exception class. |
| ArithmeticError | Arithmetic error exception class. |
| Array | Arrays provide a growable, integer indexed, in-memory store for objects. |
| AssertError | Assertion error exception class. |
| Block | The Block type is used to represent program block scope. |
| Boolean | Boolean class. |
| ByteArray | ByteArrays provide a growable, integer indexed, in-memory store for bytes. |
| Date | General purpose class for representing and working with dates, times, time spans, time zones and locales. |
| Error | Base class for error exception objects. |
| Function | The Function type is used to represent closures, function expressions and class methods. |
| InstructionError | Code (instruction) error exception class. |
| InternalError | Internal error exception class. |
| IOError | IO error exception class. |
| JSON | |
| MemoryError | Memory error exception class. |
| Namespace | Namespaces are used to qualify names into discrete spaces. |
| Null | Base type for the null value. |
| Number | The Number type is used by all numeric values in Ejscript. |
| Object | The Object Class is the root class from which all objects are based. |
| OutOfBoundsError | OutOfBounds error exception class. |
| ReferenceError | Reference error exception class. |
| Reflect | Simple reflection class. |
| RegExp | Regular expressions per ECMA-262. |
| ResourceError | Resource error exception class. |
| StateError | State error exception class. |
| Stream | Stream objects represent bi-directional streams of data that pass data elements between an endpoint known as a source or sink and a consumer / producer. |
| String | Each String object represents a single immutable linear sequence of characters. |
| SyntaxError | Syntax error exception class. |
| Type | Base class for all type objects. |
| TypeError | Type error exception class. |
| URIError | URI error exception class. |
| Void | The Void type is the base class for the undefined value. |
| XML | The XML class, and the entire XML API, is based on ECMA-357, ECMAScript for XML (E4X). |
| XMLList | The XMLList class, and the entire XML API, is based on ECMA-357, ECMAScript for XML (E4X). |