js Uint8ClampedArray All In One

js Uint8ClampedArray All In One

Uint8ClampedArray

new Uint8ClampedArray(length);
new Uint8ClampedArray(typedArray);
new Uint8ClampedArray(object);
new Uint8ClampedArray(buffer [, byteOffset [, length]]);

Uint8ClampedArray（8位无符号整型固定数组） 类型化数组表示一个由值固定在0-255区间的8位无符号整型组成的数组；
如果你指定一个在 [0,255] 区间外的值，它将被替换为0或255；
如果你指定一个非整数，那么它将被设置为最接近它的整数。
（数组）内容被初始化为0。
一旦（数组）被创建，你可以使用对象的方法引用数组里的元素，或 使用标准的数组索引语法（即使用方括号标记）。

demos

// from a length
const ui8ca = new Uint8ClampedArray(2);

ui8ca[0] = 66;
// 大于 255 ❌
ui8ca[1] = 1024;

console.log('ui8ca[0] =', ui8ca[0]);
// 42
console.log('ui8ca[1] =', ui8ca[1]);
// 255 (clamped)
console.log(ui8ca.length);
// 2
console.log(ui8ca.BYTES_PER_ELEMENT);
// 1

// from an array
var arr = new Uint8ClampedArray([12, 24]);
console.log(arr[1]);
// 24

// from another TypedArray
const arr1 = new Uint8ClampedArray([12, 24]);
const arr2 = new Uint8ClampedArray(arr1);
console.log(arr2[0]); 
// 24

// from an ArrayBuffer
const buffer = new ArrayBuffer(8);
const view = new Uint8ClampedArray(buffer, 1, 4);
// Uint8ClampedArray(4) [0, 0, 0, 0, buffer: ArrayBuffer(8), byteLength: 4, byteOffset: 1, length: 4, Symbol(Symbol.toStringTag): 'Uint8ClampedArray']

// from an iterable 
const iterable = function*(){
  // generator function
  yield* [1,2,3]; 
}();

const ui8ca = new Uint8ClampedArray(iterable);
//Uint8ClampedArray(3) [1, 2, 3, buffer: ArrayBuffer(3), byteLength: 3, byteOffset: 0, length: 3, Symbol(Symbol.toStringTag): 'Uint8ClampedArray']0: 11: 22: 3buffer: ArrayBuffer(3)  byteLength: 3byteOffset: 0length: 3Symbol(Symbol.toStringTag): "Uint8ClampedArray"[[Prototype]]: TypedArray

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8ClampedArray

Uint8Array

const steps = [...new Uint8Array(13)].map((item, i) => i + 1);
// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]

Int8Array

const steps = [...new Int8Array(13)].map((item, i) => i + 1);

TypedArray

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	-3.4E38 to 3.4E38 and 1.2E-38 is the min positive number	4	32-bit IEEE floating point number (7 significant digits e.g., 1.234567)	unrestricted float	float
Float64Array	-1.8E308 to 1.8E308 and 5E-324 is the min positive number	8	64-bit IEEE floating point number (16 significant digits e.g., 1.23456789012345)	unrestricted double	double
BigInt64Array	-2^63 to 2^63 - 1	8	64-bit two's complement signed integer	bigint	int64_t (signed long long)
BigUint64Array	0 to 2^64 - 1	8	64-bit unsigned integer	bigint	uint64_t (unsigned long long)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray#typedarray_objects

ArrayBuffer

The ArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer.

ArrayBuffer 对象用于表示一个通用的、固定长度的原始二进制数据缓冲区。

const buffer = new ArrayBuffer(8);

const view = new Int32Array(buffer);

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer

refs

---

---

©xgqfrms 2012-2020

www.cnblogs.com/xgqfrms 发布文章使用：只允许注册用户才可以访问！

原创文章，版权所有©️xgqfrms, 禁止转载 🈲️，侵权必究⚠️！

---