truth-table-poc.js

// truth table POC

let vars = ['x1', 'x2', 'x3', 'x4'],
    r = Math.pow(2, vars.length),
    str = '',
    i,
    j;

str += `\r\n\r\n`
for (i = 0; i < vars.length; i++) {
    str += `${vars[i]}\t`
}
str += `\r\n\r\n`

for (i = 0; i < r; i++) {
    for (j = 0; j < vars.length; j++) {
        let tmp = parseInt(
            i 
            / parseInt(
                (r / Math.pow(2, j)) 
                / 2
            )
        ) % 2;
        str += `${tmp}\t`
    }
    str += `\r\n`
}

console.log(str);