SOURCE

function getNum(url,temp){
    var aa
    try{
        aa = url.split('?')
    }catch(e){
        return null
    }
    var kksk = aa.shift()
    var last = url.slice(kksk.length+1,url.length)
    var a = last.split('&')
    console.log(a)
    var b = {}
    for(let i = 0; i < a.length;i++){
        var c = a[i].split('=')
        b[c[0]]=c[1]
    }
    console.log(b['a'])
    if(b[temp] === undefined){
        return null
    }else{
        return b[temp]
    }
    //console.log(b[temp])
}
getNum('https://www.qq.com?a=b','a')