Question

How to extract the last N bits of a 32-bit integer in JavaScript

Answer 1

function get_last_N_bits(number, N) {
    let mask = (1 << N) - 1;
         
    return number & mask;
}
 
const number = 441; // 00000001101-11001
const N = 5;
 
console.log(("0000000000000000" + number.toString(2)).substr(-16));
 
let lastNbits  = get_last_N_bits(number, N);
 
console.log(("0000000000000000" + lastNbits .toString(2)).substr(-16));
 
 
 
 
 
/*
run:
      
0000000110111001
0000000000011001
      
*/

 

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