第二章：Node.js中交互式运行环境--------REL

                                      

   

一：REPL运行环境概述

1 C:\Users\junliu>node  2 > foo = 'bar' ;  3 'bar'  4 >

二：在REPL运行环境中操作变量

1 C:\Users\junliu>node  2 > foo='bar'  3 'bar'  4 > var foo='bar'  5 undefined  6 >

1 console.log("foo='bar'"); //控制台窗口中将输出“bar”  2 console.log("var foo='bar'");//控制台窗口中将输出 undefined

1 //为变量赋值  2 > foo='bar';  3 'bar'  4 //输入变量名后显示变量值  5 > foo  6 'bar'  7 >

1 //将对象赋值给变量  2 > user =new Object();  3 {}  4 > user.Name='liujun';  5 'liujun'  6 > user.age='25';  7 '25'  8 //输入变量名后显示变量所引用对象的各属性名及属性值  9 > user 10 { Name: 'liujun', age: '25' } 11 >

1 //将对象赋值给变量  2 > user =new Object();  3 {}  4 > user.Name='liujun';  5 'liujun'  6 > user.age='25';  7 '25'  8 > user  9 { Name: 'liujun', age: '25' } 10 //输入变量后显示变量所引用对象的各属性名及属性值，使用“【function】”来显示函数 11 > user.setName=function(name){user.name=name}; 12 [Function] 13 > user 14 { Name: 'liujun', age: '25', setName: [Function] } 15 >

三：在REPL运行环境中使用下划线字符

1 > a=3;  2 3  3 > _+=1;  4 Expression assignment to _ now disabled.  5 4  6 > a  7 3  8 >

1 > a=3;  2 3  3 > _+=1;  4 Expression assignment to _ now disabled.  5 4  6 > a  7 3  8 >

1 C:\Users\junliu>node  2 > ['1','2','3']  3 [ '1', '2', '3' ]  4 > _.length;  5 3  6 > [1,2,3,4,5,5];  7 [ 1, 2, 3, 4, 5, 5 ]  8 > _.length;  9 6 10 > 6+3; 11 9 12 > _.toString(); 13 '9' 14 >

四：在REPL运行环境中直接运行函数

以下是在REPL运行环境中运行函数

1 C:\Users\junliu>node  2 > a=[1,1,1,3];  3 [ 1, 1, 1, 3 ]  4 > a.forEach(function(v){  5 ... console.log(v);  6 ... });  7 1  8 1  9 1 10 3

以下为：REPL运行环境将为子函数继续添加省略号

1 C:\Users\junliu>node  2 > a=[1,1,2,3,4,5]  3 [ 1, 1, 2, 3, 4, 5 ]  4 > a.forEach(function(v){  5 ... console.log(v);  6 ... });  7 1  8 1  9 2 10 3 11 4 12 5 13 undefined 14 > a.forEach(function(v){ 15 ... sf(v); 16 ... function sf(vv){ 17 ..... console.log(vv); 18 ..... } 19 ... }); 20 1 21 1 22 2 23 3 24 4 25 5 26 undefined

五：在REPL运行环境中定义并启动服务器

1 > var http=require('http');  2 undefined  3 > http.createServer(function (req,res){  4 ... res.writeHead(200, {'Content-Type': 'text/html'});  5 ...  res.write('
     ');  6 ... res.end('你好\n');  7 ... }).listen(1337, "127.0.0.1");  8 Server {  9   domain: 10    Domain { 11      domain: null, 12      _events: { error: [Function] }, 13      _eventsCount: 1, 14      _maxListeners: undefined, 15      members: [] }, 16   _events: 17    { request: [Function], 18      connection: [Function: connectionListener] }, 19   _eventsCount: 2, 20   _maxListeners: undefined, 21   _connections: 0, 22   _handle: null, 23   _usingSlaves: false, 24   _slaves: [], 25   _unref: false, 26   allowHalfOpen: true, 27   pauseOnConnect: false, 28   httpAllowHalfOpen: false, 29   timeout: 120000, 30   _pendingResponseData: 0 } 31 > console.log('Server running at http://127.0.0.1:1337/') 32 Server running at http://127.0.0.1:1337/ 33 undefined 34 >

六：REPL运行环境中的上下文对象

1 var repl = require("repl");  2 var con=repl.start("> ").context;  3 con.msg="示例消息";  4 con.testFunction=function(){console.log(con.msg);};

七：REPL运行环境中的基础命令

1 > a=[2,3,4,5,6,7];  2 [ 2, 3, 4, 5, 6, 7 ]  3 > _.length;  4 6  5 > a.forEach(function(v){  6 ... subF(v);  7 ... function subF(vv){  8 ..... console.log(vv);  9 ..... } 10 ... }); 11 2 12 3 13 4 14 5 15 6 16 7 17 undefined 18 > a.forEach(function(v){ 19 ... subF(v); 20 ... function subF(vv){ 21 ..... console.log(vv); 22 ..... break; 23 break; 24 ^^^^^ 25  26 SyntaxError: Illegal break statement 27  28 >

按两次Ctrl+c 退出REPL环境

使用.clear方法清除上下文对象中保存的所有变量和函数

使用 .help 命令显示所有的基础命令

1 a=[1,2,3,4,5,6,69,8,7,8,8];  2 a.forEach(function(v){  3 sf(v);  4 function sf(vv){  5   console.log(vv);  6   }  7 });

八：小结