Javascript

Question

在 javascript 中，您可以设置和清除单个位值，而无需使用 Number(n).toString(2)

const setBit = (num, position) => {
  let mask = 1 << position
  return num |= mask
}

const clearBit = (num, position) => {
  let mask = ~(1 << position)
  return num &= mask
}

是否可以通过类似的方式获取位值而无需调用 toString？

Answer 1

取决于结果应该是什么。布尔值 return 就足够了吗？检查指定位置的位是否设置。还是应该输出整数？

const getBit = (num, position) => {
  return (num & (2**position)) > 0;
}

console.info("Number ", 2, " on postion ", 1, getBit (2,1))
console.info("Number ", 2, " on postion ",0 , getBit (2,0))

Answer 2

const getBit = (num, position) => num >> position & 1; 

console.log( getBit(0b1010, 1) )

Javascript - 在不使用 Number(n).toString(2) 的情况下获取指定的位值作为 int

Javascript - get specified bit value as int without using Number(n).toString(2)

bitwise-operators

bitmask