如何找到typedArray的类型？

Question

要测试对象是否是数组，有一种方法 -

const myarray = [1,2,3,4]; 

Array.isArray(myarray); 

//returns true

对于类型化数组（例如 Uint8Array）是否有类似的方法？

const int8 = new Uint8Array([0,1,2,3]);

Array.isArray(int8); //returns false

如何确定一个对象是否是类型化数组，以及什么样的类型化数组？

Answer 1

您可以使用与其构造函数1的比较：const int8 = new Uint8Array([0,1,2,3]);console.log(int8.constructor === Uint8Array);// so you can dofunction checkTypedArrayType(someTypedArray) {  const typedArrayTypes = [    Int8Array,    Uint8Array,    Uint8ClampedArray,    Int16Array,    Uint16Array,    Int32Array,    Uint32Array,    Float32Array,    Float64Array,    BigInt64Array,    BigUint64Array  ];  const checked = typedArrayTypes.filter(ta => someTypedArray.constructor === ta);  return checked.length && checked[0].name || null;}console.log(checkTypedArrayType(int8));// but this can be hugely simplifiedfunction checkTypedArrayType2(someTypedArray) {  return someTypedArray &&     someTypedArray.constructor &&     someTypedArray.constructor.name ||     null;}console.log(checkTypedArrayType2(int8));// which can actually be generalized toconst whatsMyType = someObject =>   someObject &&     someObject.constructor &&     someObject.constructor.name &&     someObject.constructor.name ||     null;console.log(whatsMyType(int8));console.log(whatsMyType([1,2,3,4]));console.log(whatsMyType("hello!"))console.log(whatsMyType(/[a-z]/i))

Answer 2

对于 TypedArrays，实际上有一个等效于Array.isArray的，可以在ArrayBuffer构造函数上访问：ArrayBuffer.isView.但是请注意，它也会为DataView对象返回 true ，因此如果您真的想知道一个对象是否为 TypedArray，您可以简单地执行以下操作：function isTypedArray( arr ) {  return ArrayBuffer.isView( arr ) && !(arr instanceof DataView);}function test( val ) {  console.log( isTypedArray( val ) );}test( false ); // falsetest( null ); // falsetest( [] ); // falsetest( new ArrayBuffer( 12 ) ); // falsetest( new DataView( new ArrayBuffer( 12 ) ) ); // falsetest( new Uint8Array( 12 ) ); // true;test( new BigInt64Array( 12 ) ); // true;但这不会为您提供该 TypedArray 的特定类型。TypedArray 的原型公开了一个BYTES_PER_ELEMENT属性，但仅此而已......构造函数上有一个可以访问的.name属性，它本身可以通过.constructor每个实例的属性访问，但可以设置，IE 不支持。但是，如果这对您来说不是问题，那么只需：function getType( arr ) {  return isTypedArray( arr ) && arr.constructor.name;}function isTypedArray( arr ) {  return ArrayBuffer.isView( arr ) && !(arr instanceof DataView);}function test( val ) {  console.log( getType( val ) );}test( [] ); // falsetest( new ArrayBuffer( 12 ) ); // falsetest( new DataView( new ArrayBuffer( 12 ) ) ); // falsetest( new Uint8Array( 12 ) ); // "Uint8Array";test( new BigInt64Array( 12 ) ); // "BigInt64Array";如果您需要支持 IE，instanceof也可以选择独立测试所有可能的 TypedArrays 构造函数：const typedArrays = [ 'Int8', 'Uint8', 'Uint8Clamped', 'Int16', 'Uint16', 'Int32', 'Uint32', 'Float32', 'Float64', 'BigInt64', 'BigUint64'].map( (pre) => pre + 'Array' );function getType( arr ) {  return isTypedArray( arr ) &&    typedArrays.find( (type) => arr instanceof window[ type ] );}function isTypedArray( arr ) {  return ArrayBuffer.isView( arr ) && !(arr instanceof DataView);}function test( val ) {  console.log( getType( val ) );}test( [] ); // falsetest( new Uint8Array( 12 ) ); // Uint8Arraytest( new Int16Array( 12 ) ); // Int16Arraytest( new Float32Array( 12 ) ); // Float32Array

Answer 3

另一种方法可能是，您可以使用BYTES_PER_ELEMENT类型化数组的属性https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/BYTES_PER_ELEMENTArray.isTypedArray = function(inArray) {  if (inArray) {    const prototype = Object.getPrototypeOf(inArray);    return prototype ? prototype.hasOwnProperty("BYTES_PER_ELEMENT") : false;  }  return false;};正如其他答案中提到的，要获得实际类型，您可以使用constructor.name. 重用上面的isTypedArray函数，你可以这样写。function getType(obj){    return Array.isTypedArray(obj) ? obj.constructor.name: (typeof obj)}示例代码和 console.logsArray.isTypedArray = function(inArray){    if(inArray){        const prototype = Object.getPrototypeOf(inArray);        return prototype ? prototype.hasOwnProperty("BYTES_PER_ELEMENT") : false;    }    return false;}console.log(" 'Iam' a typed array 👉 ", Array.isTypedArray([1,2,3]));console.log("[1,2,3] is typed array 👉 ", Array.isTypedArray([1,2,3]));console.log("new Int8Array([1,2,3]) is typed array 👉 ", Array.isTypedArray(new Int8Array([1,2,3])));console.log("new BigUint64Array() is typed array 👉 ", Array.isTypedArray(new BigUint64Array()));console.log("new Uint8ClampedArray([1,2,3]) is typed array 👉 ", Array.isTypedArray(new Uint8ClampedArray([1,2,3])));console.log("new Float32Array([1,2,3]) is typed array 👉 ", Array.isTypedArray(new Float32Array([1,2,3])));console.log("new BigUint64Array() is typed array 👉 ", Array.isTypedArray(new BigUint64Array()));console.log("new Set() is typed array 👉 ", Array.isTypedArray(new Set()));console.log("null is typed array 👉 ", Array.isTypedArray(null));console.log("undedined is typed array 👉 ", Array.isTypedArray(undefined));console.log("{} is typed array 👉 ",Array.isTypedArray({}));function getType(obj){    return Array.isTypedArray(obj) ? obj.constructor.name: (typeof obj)}console.log("Type of Array 👉 ", getType(new Array()));console.log("Type of Int8Array 👉 ", getType(new Int8Array()));console.log("Type of Uint8Array 👉 ",getType( new Uint8Array()));console.log("Type of Uint8ClampedArray 👉 ",getType( new Uint8ClampedArray()));console.log("Type of Int16Array 👉 ", getType(new Int16Array()));console.log("Type of Float32Array 👉 ", getType(new Float32Array()));console.log("Type of BigInt64Array 👉 ", getType(new BigInt64Array()));console.log("Type of BigUint64Array 👉 ", getType(new BigUint64Array()));