function isNegative(element, index, array) {
  return element < 0;
}

const int8 = new Int8Array([-10, 20, -30, 40, -50]);
const positives = new Int8Array([10, 20, 30, 40, 50]);

console.log(int8.some(isNegative));
// expected output: true

console.log(positives.some(isNegative));
// expected output: false