1.=>什么用法
=>是es6语法中的arrow function
(x) => x + 6
相当于
function(x){
return x + 6;
};
2. 2017nodejs使用报告
https://blog.risingstack.com/what-is-node-js-used-for-2017-survey/
3. Array.prototype.map()
数组便利，实际例子：
var array1 = [1, 4, 9, 16];
// pass a function to map
const map1 = array1.map(x => x * 2);
console.log(map1);
// expected output: Array [2, 8, 18, 32]
4. fetch()
可以方便的调用ajax,返回promise对象
http://blog.csdn.net/sinat_17775997/article/details/70054674
