padStart应用

// 将一个ipv4地址转换为10进制数输出
// eg: 192.168.1.1

function translateIP2Dig(ipStr) {
let ipArr = ipStr.split('.')
let resArr = []
ipArr.forEach(item => {
let str = parseInt(item).toString(2)
str = str.padStart(8, 0)
resArr.push(str)
})
return parseInt(resArr.join(''), 2)
}
var res1 = translateIP2Dig('192.168.1.1')
console.log(res1)