trying to make an lfsr in js

Question

i'm trying to make an lfsr in js, on its head every thing is looking good, i'm using strings and im converting them back and forth to get the last bit, my problem is printing the number i'm trying to make a large hex number, my logic is give me a seed and a length and the function should generate a hex number in that length.

function lfsr(seed, length ){
    var arr = Array.from(seed.toString(2));
    result ="";
    for (var i = 0; i < lenght; i++) {
        let _last = parseInt(arr.pop());
        let _blast = parseInt(arr[arr.length - 1])
        let _newbit = _last ^ _blast;
        arr.splice(0 , 0 ,_newbit.toString());
        result += _newbit.toString();
    }
    return  parseInt(result, 2).toString(16); 

this is my code, i ran some tests and got a good output, but when i pring the answer i get this output:

be92231350d87800000000000

oh, and my input is this:

var ans = lfsr(6543123123798,100);

any idea how to get rid of the excess 0's and get what I need? thanks for your time.

Answer 1

i've changed the code to be :

function lfsr(seed, length,base){
    var arr = Array.from(seed.toString(base));
    var result ="";
    for (var i = 0; i < length ; i++) {
        let _newbit = parseInt(arr.pop(),16) ^ parseInt(arr[arr.length - 1],base);
        arr.splice(0 , 0 ,_newbit.toString(base));
        result += _newbit.toString(base); 
    }
    return  result; 
}

and it solved my problem. any one is welcome to use it.