git clone https://github.com/jjay/construct.js.git
cd construct.js
./build.sh
cp construct.js /path/to/static/files

with ( construct ){
    struct = Struct("attempt_1",
        UBInt8("Age"),
        SBInt16("Hairs"),
        UBInt32("Weight"),
        Struct("prefs",
            UBInt8("a"),
            UBInt8("b")
        )
    )
}

result = struct.parse('\x01\x32\x21\x00\x00\x00\xff\x01\x02')
console.log(result)

//> { Age: 1, Hairs: 12833, Weight: 255, prefs: { a: 1, b: 2 } }