Answer 1

const arr1 = ["A1", "A2", "B1", "B2", "C1", "C2", "D1", "D2"];
const arr2 = ["A", "B", "C", "D"];
const arr=[...arr1,...arr2].sort((a,b)=>{
    if(a.length===1){
        a+="3"
    }
    if(b.length===1){
        b+="3"
    }
    return a.localeCompare(b)
})
console.log(arr);

合并排序就完事了啊；考察的什么呢？

Answer 2

const isUrl = urlStr => {
    try {
        const { href, origin, host, hostname, pathname } = new URL(urlStr)
        return href && origin && host && hostname && pathname && true
    } catch (e) {
        return false
    }
}