blobToArrayBuffer(blob, callback) {
	let reader = new FileReader();
	reader.onload = function() {
		return callback(this.result);
	reader.readAsArrayBuffer(blob);
                    
2. arrayBuffer 转 Uint8Array
                                    
var u8a = new Uint8Array(arrayBuffer);
                    
3.Uint8Array 转 String
                                    
uint8ArrayToString(u8a) {
	var dataStr = "";
	for(var i=0;i
                                
js 将 blob 转 arrayBuffer 、 arrayBuffer 转 Uint8Array 、 Uint8Array 转 String 的方法
                                                                                
1. blob 转 arrayBuffer
                                                                                    
2. arrayBuffer 转 Uint8Array
                                                                                    
3.Uint8Array 转 String