hao2 access prototype of a javascript "arraylike object"?

in my language i do .eren instead of .length, which i can do for arrays and strings via prototype as seen here. but the "arguments" of a function is an "arraylike object" and i have not yet found how to access its prototype. nowhere online seems to say. i would like to similarly use .eren to access .length on arguments without the step of converting arguments to array. hao access prototype?