回答

1、arraybuffer类型转16进制字符串

function buf2hex(buffer) {

return Array.prototype.map.call(new Uint8Array(buffer), x => ('00' +
x.toString(16)).slice(-2)).join('');

}

function hex2buf(hex){
    var typedArray = new Uint8Array(hex.match(/[\da-f]{2}/gi).map(function (h) {
       return parseInt(h, 16)
     }))
    return typedArray.buffer
}

function hex2buf(hex) {

    var typedArray = new Uint8Array(hex.match(/[\da-f]{2}/gi).map(function (h) {
        return parseInt(h, 16)
    }))
    return typedArray.buffer
}

function buf2hex(buffer) {

    return Array.prototype.map.call(new Uint8Array(buffer), x => ('00' +
        x.toString(16)).slice(-2)).join('');

}
var hex = 'aa5504b10000b5';
let buf = hex2buf(hex);
console.log(buf);

let oldhex = buf2hex(buf);
console.log(oldhex);

附加知识：

一、普通字符转二进制：

var code = "a"
var rs = code.charCodeAt() //获得"a"在ASCII表中对应的十进制整数，
console.log(rs)//97

二、二进制转十六进制

var code = 97
var rs1 = code.toString(16) //获得97对应的十六进制整数
console.log(rs1)//61

补充：普通字符转十六进制连写consle.log("a".charCodeAt().toString(16))

三、十六进制转二进制

var num = 61
var val = parseInt(num,16)//第二参数告诉函数，num是16进制整数，parseInt会帮我们解析成对应的十进制整数
console.log(val) //97

四、二进制转普通字符

var num = 97
var val1 = String.fromCharCode(num)//获得十进制整数97在ASCII表中对应的字符
console.log(val1)//a