前端正则表达式积累合集 （1）

1. 格式化货币(仅转换小数点前的整数部分)
   实现效果，遵循的原则：
2. ==> 123,456,789
   123456789.1234 ==> 123,456,789.123

const formatMoney = (money) =>{
return money.replace( new RegExp( `(?!^)(?=(\\d{3})+${money.includes('.') ? '\\.' : '$'})`, 'g'), ',' )  )
}

formatMoney('123456789') // '123,456,789'
formatMoney('123456789.123') // '123,456,789.123'
formatMoney('123') // '123'
formatMoney('123456789.123456')//'123,456,789.123456'

2. 实现trim功能的两种方式
   去掉字符串首尾的空格
   方法1：

const trim1 = (str) => {
return str.replace( /^\s*|s*$/g, '' )
}

const string = '      hello world               '
const noSpaceString = 'hello world'
const trimString = trim1(  string)

console.log(string) //      hello world               
console.log(trimString, trimString === noSpaceString)//hello world, true
console.log(string)  //      hello world               

方法2：

const trim2 = (str) => {
  return str.replace(/^\s*(.*?)\s*$/g, '$1')    
}

const string = '   hello medium   '
const noSpaceString = 'hello medium'
const trimString = trim2(string)

console.log(string)  //   hello medium   
console.log(trimString, trimString === noSpaceString)//hello medium,true
console.log(string)//   hello medium   

3. 解析链接上的搜索参数

// url https://qianlongo.github.io/vue-demos/dist/index.html?name=fatfish&age=100#/home

const getQueryByName = (name) => {
  const queryNameRegex = new RegExp(`[?&]${name}=([^&]*)(&|$)`)
  const queryNameMatch = window.location.search.match(queryNameRegex)
  return queryNameMatch ? decodeURIComponent(queryNameMatch[1]) : ''
}

const name = getQueryByName('name')
const age = getQueryByName('age')

console.log(name, age) // fatfish, 100

4. 驼峰式字符串
   示例：
   foo Bar => fooBar
   foo-bar---- => fooBar
   foo_bar__ => fooBar

const camelCase = (string) => {
  const camelCaseRegex = /[-_\s]+(.)?/g
  return string.replace(camelCaseRegex, (match, char) => {
    return char ? char.toUpperCase() : ''
  })
}

console.log(camelCase('foo Bar')) // fooBar
console.log(camelCase('foo-bar--')) // fooBar
console.log(camelCase('foo_bar__')) // fooBar

5. 将字符串的首字母转换为大写
   请将 hello world 转换为 Hello World。

const capitalize = (string) => {
  const capitalizeRegex = /(?:^|\s+)\w/g
  return string.toLowerCase().replace(capitalizeRegex, (match) => match.toUpperCase())
}

console.log(capitalize('hello world')) // Hello World
console.log(capitalize('hello WORLD')) // Hello World

6. 按照3-4-4格式划分电话号码

let mobile = '18379836654' 
let mobileReg = /(?=(\d{4})+$)/g 

console.log(mobile.replace(mobileReg, '-')) // 183-7983-6654