JavaScript: ArrayBuffer and TypedArray

JavaScript typed arrays split the implementation into buffers and views. A buffer (implemented by the ArrayBuffer object) is an object representing a chunk of data; it has no format to speak of and offers no mechanism for accessing its contents. In order to access the memory contained in a buffer, you need to use a view. A view provides a context — that is, a data type, starting offset, and the number of elements — that turns the data into a typed array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Typed_arrays

Type	Value Range	Size in bytes	Description	Web IDL type	Equivalent C type
Int8Array	-128 to 127	1	8-bit two’s complement signed integer	byte	int8_t
Uint8Array	0 to 255	1	8-bit unsigned integer	octet	uint8_t
Uint8ClampedArray	0 to 255	1	8-bit unsigned integer (clamped)	octet	uint8_t
Int16Array	-32768 to 32767	2	16-bit two’s complement signed integer	short	int16_t
Uint16Array	0 to 65535	2	16-bit unsigned integer	unsigned short	uint16_t
Int32Array	-2147483648 to 2147483647	4	32-bit two’s complement signed integer	long	int32_t
Uint32Array	0 to 4294967295	4	32-bit unsigned integer	unsigned long	uint32_t
Float32Array	1.2×10-38 to 3.4×1038	4	32-bit IEEE floating point number (7 significant digits e.g., 1.123456)	unrestricted float	float
Float64Array	5.0×10-324 to 1.8×10308	8	64-bit IEEE floating point number (16 significant digits e.g., 1.123...15)	unrestricted double	double
BigInt64Array	-263 to 263-1	8	64-bit two’s complement signed integer	bigint	int64_t (signed long long)
BigUint64Array	0 to 264-1	8	64-bit unsigned integer	bigint	uint64_t (unsigned long long)

Example

> u8view
Uint8Array [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ]

> u32view
Uint32Array [ 0, 0, 0, 0 ]

> u8view[0] = 255
255
> u32view[0]
255

// 257 is greater than 255, will become 1
// 1[00000001] = 257 => 1
// 1[00000000] = 256 => 0
> u8view[1] = 257
257

> u8view[1]
1

// 32 byte view, the first element is 256 (u8view[1]) + 255(u8view[0]) = 511
> u32view[0]
511

> u8view[3] = 1
1

// 32 byte view, the first element is (2^24 + 1) + (2^16 * 0) + (2^8 + 1) + 255
//                                    16777216   + 0          + 256       + 255 = 16777727
> u32view[0]
16777727

> u8view
Uint8Array [ 255, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ]

> u32view
Uint32Array [ 16777727, 0, 0, 0 ]