该类型 
这个已建入 JavaScript 值的类型是什么 ? 作品跨现实,没有 instanceof,不能被一个 constructor 属性.
示例
var whichBuiltinType = require('which-builtin-type');
var assert = require('assert');
assert.equal(undefined, whichBuiltinType(undefined));
assert.equal(null, whichBuiltinType(null));
assert.equal('Boolean', whichBuiltinType(false));
assert.equal('Boolean', whichBuiltinType(true));
assert.equal('Array', whichBuiltinType([]));
assert.equal('Object', whichBuiltinType({}));
assert.equal('RegExp', whichBuiltinType(/a/g));
assert.equal('RegExp', whichBuiltinType(new RegExp('a', 'g')));
assert.equal('Date', whichBuiltinType(new Date()));
assert.equal('Number', whichBuiltinType(42));
assert.equal('Number', whichBuiltinType(NaN));
assert.equal('Number', whichBuiltinType(Infinity));
assert.equal('Number', whichBuiltinType(new Number(42)));
assert.equal('String', whichBuiltinType('foo'));
assert.equal('String', whichBuiltinType(Object('foo')));
assert.equal('Function', whichBuiltinType(function () {}));
assert.equal('GeneratorFunction', whichBuiltinType(function* () {}));
assert.equal('Function', whichBuiltinType(x => x * x));
assert.equal('Array', whichBuiltinType([]));
assert.equal('Int8Array', whichBuiltinType(new Int8Array()));
assert.equal('Uint8Array', whichBuiltinType(new Uint8Array()));
assert.equal('Uint8ClampedArray', whichBuiltinType(new Uint8ClampedArray()));
assert.equal('Int16Array', whichBuiltinType(new Int16Array()));
assert.equal('Uint16Array', whichBuiltinType(new Uint16Array()));
assert.equal('Int32Array', whichBuiltinType(new Int32Array()));
assert.equal('Uint32Array', whichBuiltinType(new Uint32Array()));
assert.equal('Float32Array', whichBuiltinType(new Float32Array()));
assert.equal('Float64Array', whichBuiltinType(new Float64Array()));
assert.equal('BigInt64Array', whichBuiltinType(new BigInt64Array()));
assert.equal('BigUint64Array', whichBuiltinType(new BigUint64Array()));
测试
仅仅复制回转, npm install运行 npm test
