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Node socket. io event Usage Details, nodesocket. io
The socket. io class library can not only send messages to each other, but also send events to each other through the emit method of the socket port object.
In the previous event, emit said that it was used to manually trigger the event.
Copy codeThe Code is as follows:
Socket. emit (event, data, function (data1, data2 ......){
});
When you use the emit method to send events, you can use the on method of the socket port object on the other end to listen once.
Copy codeThe Code is as follows:
Socket. on (event, function (data, fn ){
});
Socket. once (event, function (data, fn ){
})
The parameter data in the preceding callback function: the data carried by the event sent by the other party,
Fn: the callback function specified by the other party when sending the event.
Case 1: After the server and the client are connected, a news event is sent to the client. The event carries an object whose hello attribute value is "hello ". when receiving the my other event from the client, output "server receives data" + data contained in the event sent by the client in the console.
Server code, server. js
Copy codeThe Code is as follows:
Var http = require ("http ");
Var sio = require ("socket. io ");
Var fs = require ("fs ");
Var server = http. createServer (function (req, res ){
Res. writehead( 200, {"Content-type": "text/html "});
Res. end (fs. readFileSync ("./index.html "));
});
Server. listen (1337 );
Var socket = sio. listen (server );
Socket. on ("connection", function (socket ){
Socket. emit ("news", {hello: "hello "});
Socket. on ("my other event", function (data ){
Console. log ("server received information % j", data );
});
});
Client index.html code:
Copy codeThe Code is as follows:
<! DOCTYPE html>
<Html>
<Head lang = "en">
<Meta charset = "UTF-8">
<Title> </title>
<Script src = "/socket. io/socket. io. js"> </script>
<Script>
Var socket = io. connect ();
Socket. on ("news", function (data ){
Console. log (data. hello );
Socket. emit ("my other event", {my: "data "});
});
</Script>
</Head>
<Body>
</Body>
Running result :,
We can find that the execution is always on the listener rather than the manual execution.
Case 2: Specify the callback function when you manually trigger the event.
After the client and the server are connected, the setName event is sent to the client. The event carries "Zhang San". When the event is triggered, a callback function is specified. The callback function outputs two parameter values to the console.
Copy codeThe Code is as follows:
Var http = require ("http ");
Var sio = require ("socket. io ");
Var fs = require ("fs ");
Var server = http. createServer (function (req, res ){
Res. writehead( 200, {"Content-type": "text/html "});
Res. end (fs. readFileSync ("./index.html "));
});
Server. listen (1337 );
Var socket = sio. listen (server );
Socket. on ("connection", function (socket ){
Socket. emit ("setName", "Zhang San", function (data1, data2 ){
Console. log (data1 );
Console. log (data2 );
});
});
Copy codeThe Code is as follows:
<! DOCTYPE html>
<Html>
<Head lang = "en">
<Meta charset = "UTF-8">
<Title> </title>
<Script src = "/socket. io/socket. io. js"> </script>
<Script>
Var socket = io. connect ();
Socket. on ("setName", function (name, fn ){
Console. log (name );
Fn ("Li Si", "Wang Wu ");
});
</Script>
</Head>
<Body>
</Body>
</Html>
Execution result:
The callback function is actually executed by the trigger side.
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