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('<head><meta charset="utf-8"/></head>');
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
