node.js – Nodejs异步混淆

function first() {
    var object = {
        aProperty: 'stuff',anArray: ['html','html'];
    };
    second(object);
}

function second(object) {
    for (var i = 0; i < object.anArray.length; i++) {
        third(object.anArraY[i]);
    };
}

function third(html) {
    // Parse html
}
first();

“全局”是任何I / O都是非阻塞的,并且在JavaScript中异步执行;因此,如果您进行任何数据库查找,从套接字(例如在http服务器中)读取数据,读取或写入磁盘等文件,则必须使用异步代码.这是必要的,因为事件循环是单个线程,如果I / O不是非阻塞,则程序在执行时会暂停.

您可以构建代码,以便嵌套更少;例如：

var fs = require('fs');
var MysqL = require('some_MysqL_library');

fs.readFile('/my/file.txt','utf8',processFilE);

function processFile(err,data) {
  MysqL.query("INSERT INTO tbl SET txt = '" + data + "'",doneWithsql);
}

function doneWithsql(err,results) {
  if(err) {
    console.log("There was a problem with your query");
  } else {
    console.log("The query was successful.");
  }
}

还有流量控制库,如async(我个人选择),以帮助避免大量嵌套回调.

可能感兴趣：this screencast I created on the subject.