浏览器中window.location属性 和window.history属性：
export function FrontRouter() {
this.routes = {};
this.preHash = '/';
this.curHash = '/';
window.addEventListener('load', this.resolve.bind(this), false);
window.addEventListener('hashchange', this.resolve.bind(this), false);
}
FrontRouter.prototype.route = function(path, callback) {
this.routes[path] = callback || function() {};
};
FrontRouter.prototype.back = function() {
location.hash = '#' + this.preHash;
console.log('pre_hash:', location.hash);
}
FrontRouter.prototype.resolve = function() {
this.preHash = this.curHash;
this.curHash = location.hash.slice(1) || '/';
typeof this.routes[this.curHash] === 'function' &&
this.routes[this.curHash]();
};
