分析拆解 url 各个部分

location 和 history

// location
console.log(location.href)
// http://localhost/test/test.html?a=100#100
console.log(location.protocol) // http:
console.log(location.host) // localhost
console.log(location.search) // ?a=100
console.log(location.hash) // #100
console.log(location.pathname) // /test/test.html
// history
history.back() // 后退
history.forward() // 前进