迅雷前端的两道编程题题目

//第一道 EventEmitter类

	
	

		class EventEmitter {
	

	

		on(event, fn) {
	

	

		this._callbacks = this._callbacks || {};
	

	

		(this._callbacks['$' + event] = this._callbacks['$' + event] || []).push(fn);
	

	

		return this;
	

	

		}
	

	

		once(event, fn) {
	

	

		function on() {
	

	

		this.remove(event, on);
	

	

		fn.apply(this, arguments);
	

	

		}
	

	

		on.fn = fn;
	

	

		this.on(event, on);
	

	

		return this;
	

	

		}
	

	

		remove(event, fn) {
	

	

		this._callbacks = this._callbacks || {};
	

	

		if (0 == arguments.length) {
	

	

		this._callbacks = {};
	

	

		return this;
	

	

		}
	

	

		var callbacks = this._callbacks['$' + event];
	

	

		if (!callbacks) return this;
	

	

		if (1 == arguments.length) {
	

	

		delete this._callbacks['$' + event];
	

	

		return this;
	

	

		}
	

	

		var cb;
	

	

		for (var i = 0; i < callbacks.length; i++) {
	

	

		cb = callbacks[i];
	

	

		if (cb === fn || cb.fn === fn) {
	

	

		callbacks.splice(i, 1);
	

	

		break;
	

	

		}
	

	

		}
	

	

		return this;
	

	

		}
	

	

		emit(event) {
	

	

		this._callbacks = this._callbacks || {};
	

	

		var args = [].slice.call(arguments, 1),
	

	

		callbacks = this._callbacks['$' + event];
	

	

		if (callbacks) {
	

	

		callbacks = callbacks.slice(0);
	

	

		for (var i = 0, len = callbacks.length; i < len; ++i) {
	

	

		callbacks[i].apply(this, args);
	

	

		}
	

	

		}
	

	

		return this;
	

	

		}
	

	

		}
	

	

		
	

	

		//第二道 学生排序
	

	

		
		

			
			

				function sortStudents(obj1, obj2) {
			

			

				if (obj1["class"] === obj2["class"]) {
			

			

				var val1 = obj1["score"];
			

			

				var val2 = obj2["score"];
			

			

				if (val1 < val2) {
			

			

				return 1;
			

			

				} else if (val1 > val2) {
			

			

				return -1;
			

			

				} else {
			

			

				return 0;
			

			

				}
			

			

				} else if(obj1['class'] === obj2['class'] && obj1["score"] === obj2["score"]){
			

			

				return 0;
			

			

				} else {
			

			

				var val1 = obj1["class"];
			

			

				var val2 = obj2["class"];
			

			

				if (val1 < val2) {
			

			

				return -1;
			

			

				} else if (val1 > val2) {
			

			

				return 1;
			

			

				} else {
			

			

				return 0;
			

			

				}
			

			

				}
			

			

				}
			

			

				var arr = [{ "name": "张三", "class": 2, "score": 64 }, { "name": "李四", "class": 1, "score": 80 }, { "name": "王五", "class": 1, "score": 80 }, { "name": "赵六", "class": 4, "score": 94 }];
			

			

				console.log(arr.sort(sortStudents));