learnyounode Lesson 3

课程目标:

Write a program that uses a single synchronous filesystem operation to
  read a file and print the number of newlines (\n) it contains to the
  console (stdout), similar to running cat file | wc -l.

My Solution:

const fs = require("fs");
const buffer = fs.readFileSync(process.argv[2]);

const result = buffer.toString().split("\n").length - 1;
console.log(result);

// note you can avoid the .toString() by passing 'utf8' as the
// second argument to readFileSync, then you'll get a String!
//
// fs.readFileSync(process.argv[2], 'utf8').split('\n').length - 1

这节课主要讲的 fs 的同步读取文件方法readFileSync,第一个参数是文件路径，第二个参数是编码格式。返回的是node特有的buffer格式，可以通过不同方法转换所需要的类型（eg.toString()）

好了认识了第一个 node 核心模块（core modules）fs.过关！