js-判断android,ios,pc三端环境

js-判断android,ios,pc三端环境
用了个复杂的一句话写法替代if判断

写法一

function getPlatform () {
  let u = navigator.userAgent
  const isAndroid = u.indexOf('Android') > - 1 || u.indexOf('Adr') > -1
  const isIos = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/)
  if(isAndroid) {
    return 'android'
  } else if (isIos) {
    return 'ios'
  } else {
    return 'pc'
  }
}
1
2
3
4
5
6
7
8
9
10
11
12

写法二

function getPlatform () {
  const u = navigator.userAgent
  const m = new Map([
    [
      () => !~~u.indexOf('Android') || !~~u.indexOf('Adr'),'android'
    ],
    [
      () => !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/),'ios'
    ],
    [()=>true, 'pc']
  ])
  return [...m].map(([f,r]) => f() && r).filter(v=>v).toString()
}
getPlatform()
1
2
3
4
5
6
7
8
9
10
11
12
13
14

写法三

function getPlatform () {
  const u = navigator.userAgent
  const m = new Map([
    [
      () => !~~u.indexOf('Android') || !~~u.indexOf('Adr'),'android'
    ],
    [
      () => !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/),'ios'
    ],
    [()=>true, 'pc']
  ])
  return [...m].find(([f,_]) => f()).slice(1).toString()
}
getPlatform()
1
2
3
4
5
6
7
8
9
10
11
12
13
14