let 
	 arr = [],
     arr2 = [],
	 arr3 = [];

		//正常写法
		for (var i=0; i<10; i++) {
			arr[i] = function () {
				console.log(i)
			}
		}

		console.log(arr[5]())		//10

		//闭包
		for (var i=0; i<10; i++) {
			arr2[i] = function (num) {
				return function () {
					console.log(num)
				}
			}(i)
		}

		console.log(arr2[5]())		//5
		
		//es6
		for (let i=0; i<10; i++) {
			arr3[i] = function () {
				console.log(i)
			}
		}

		console.log(arr3[5]())	//5

** 使用了es6的let声明，使用较新的chrome浏览器查看不会报错 **