node.js - 一个fs.statSync的问题

Question

"use strict";
var fs = require('fs');
var colors = require('colors/safe');
fs.readdir(process.cwd(), function (err, files) {
    files.forEach(function (item, index, array) {
        fs.statSync(item, function (err, stat) {
            if (stat.isDirectory()) {
                console.log(colors.blue(item + '/'));
            }
            else if (stat.isFile()) {
                console.log(colors.green(item));
            }
        });
    });
});

这个程序本来是想打印出当前目录下的文件的,但是如果我把fs.stat换成fs.statSync后,就无法输出了,这是为啥呢? node的版本是v0.12.7

Answer 1

Because statSync is a synchronization method, the result is obtained directly, that is, stat = fs.statSync(item) and then judge stat.isDirectory()

Answer 2

Let’s take a look at the many methods provided by the File System module of nodejs. These methods can be roughly divided into two categories: one is asynchronous + callback; the other is synchronous. Among them, stat belongs to the former, and statSync belongs to the latter. Let’s take a look at the difference:

1.异步版：fs.stat(path,callback):
    path是一个表示路径的字符串,callback接收两个参数(err,stats),其中stats就是fs.stats的一个实例；
  
2.同步版：fs.statSync(path)
   只接收一个path变量，fs.statSync(path)其实是一个fs.stats的一个实例；

3.再来看fs.stats有以下方法:
    stats.isFile()
    stats.isDirectory()
    stats.isBlockDevice()
    stats.isCharacterDevice()
    stats.isSymbolicLink() (only valid with fs.lstat())
    stats.isFIFO()
    stats.isSocket()

After reading this, you will understand.