# Working with Data

h5 provides seamless integration between standard .NET data types and JavaScript primitives.

# Primitive Types

Most C# primitive types map directly to JavaScript primitives:

C# Type	JavaScript Type	Notes
`string`	`string`	UTF-16 strings
`bool`	`boolean`	`true` / `false`
`byte`, `sbyte`	`number`	Integer
`short`, `ushort`	`number`	Integer
`int`, `uint`	`number`	Integer
`long`, `ulong`	`number`	Uses `BigInt` or library emulation depending on config
`float`, `double`	`number`	IEEE 754 floating point
`decimal`	`number`	Warning: Precision loss possible if mapped to `number`
`char`	`number`	UTF-16 code unit

# Integers & Floating Point

JavaScript uses 64-bit floating point numbers for all numeric types by default. h5 handles integer arithmetic correctly, including overflow/underflow behavior (configurable via overflowMode).

However, for long (64-bit integer), h5 can use BigInt if supported by the target environment, or a custom Long implementation.

# Arrays

C# arrays are mapped to JavaScript arrays.

int[] numbers = new int[] { 1, 2, 3 };

Becomes:

var numbers = [1, 2, 3];

You can use standard array methods and indexers. However, note that C# arrays are fixed-size, while JavaScript arrays are dynamic. h5 enforces C# semantics where possible.

# Collections

h5 includes implementations of standard generic collections like List<T>, Dictionary<TKey, TValue>, HashSet<T>, etc.

var list = new List<string> { "a", "b" };
list.Add("c");

var dict = new Dictionary<string, int>();
dict["key"] = 123;

These behave exactly as you expect from .NET, including proper equality comparison for keys in dictionaries.

# DateTime

System.DateTime is supported and backed by JavaScript's Date object, but provides the full .NET API surface including time zones and formatting.