Blob()构造方法返回一个新的Blob对象. 内容是包含参数array的二进制字节流. 语法 var aBlob = new Blob( array, options ); 参数 array is an Array of ArrayBuffer, ArrayBufferView, Blob, DOMString objects, or a mix of any of such objects, that will be put inside the Blob. DOMStrings are e