【发布时间】：2018-03-05 11:29:10
【问题描述】：
我对此很陌生，我不明白为什么我的脚本没有从 html 加载...这是我的主要问题。
然后，我想获取可用 COM 端口的列表并将某些内容发送到可用端口。我安装了串口 v 6.1.1。我用标签创建了 index.html，但似乎没有工作（加载）。当这工作时，我想在 html 上获取表单以获取数据（输入文本）并将其传递给 received.js。 js文件中可能有错误，但由于没有加载任何脚本而无法判断。
控制台返回错误：
SyntaxError: expected expression, got '<' [Learn More] index.js:1
SyntaxError: expected expression, got '<' [Learn More] received.js:1
起点是 server.js:
var http = require('http');
var fs = require('fs');
var http_IP='127.0.0.1';
var http_port = 9876;
//generate html
function onRequest(request, responce){
responce.writeHead(200,{'Content-type': 'text/html'});
fs.readFile('./index.html', null, function(error, data){
if(error){
responce.writeHead(404);
responce.write('File not found');
}else{
responce.write(data);
}
responce.end();
});
}
http.createServer(onRequest).listen(http_port);
console.log('listening on http://' + http_IP + ':' + http_port);
index.js（警报或控制台也不在打印消息）
console.log("Hello");
alert('Hello');
var serialport = require('serialport');
// list serial ports:
serialport.list(function (err, ports) {
ports.forEach(function(port) {
console.log(port.comName);
});
});
serialport.list((err, ports) => {
console.log('ports', ports);
if (err) {
document.getElementById('error').textContent = err.message
return
} else {
//var port = new serialport('"FTDIBUS\VID_0403+PID_6001+FT9PQV36A\0000"', { baudRate: 115200})
document.getElementById('error').textContent = message
}
if (ports.length === 0) {
document.getElementById('error').textContent = 'No ports discovered'
}
const headers = Object.keys(ports[0])
const table = createTable(headers)
tableHTML = ''
table.on('data', data => tableHTML += data)
table.on('end', () => document.getElementById('ports').innerHTML = tableHTML)
ports.forEach(port => table.write(port))
table.end();
});
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width-device-width, initial-scale=1.0"></>
<meta http-equiv="X_UA-Compatible" content="ie=edge" ></>
<title>My Serial Port v1</title>
</head>
<body>
<h3 id="h3">Serial Port v1</h3>
<FORM class="form" NAME="myform" ACTION="" METHOD="POST" onsubmit="return false">Enter command to process (without "()"): <BR>
<INPUT TYPE="text" NAME="inputbox" id ="inputbox" VALUE="">
<INPUT TYPE="button" NAME="button" id = "send_button" Value="Click" onClick="">
</FORM>
<script type"text/javascript" src="index.js"></script>
<script src="received.js">
</script>
</body>
</html>
received.js
const serialport = require('serialport');
var ready ='';
const portName = 'COM20';
var port = new serialport(portName, { parser: serialport.parsers.readline('\r\n'), baudRate: 19200});
//**** SENDING
port.open(function(err){
if(err){
return console.log('Error opening port: ', err.message);
}
var button = document.getElementById('send_button');
var form = document.getElementsByName('myform');
console.log("")
// var value= '';
// handling html form
button.onclick = function myFormHandler(){
var value = button.form.inputbox.value;
console.log('Entered value: ', value);
// storing entered value
localStorage.setItem('command_value', value);
command_optics = value;
console.log('Value of value', value);
console.log('Value of command_optics', command_optics);
// recalling entered value
var command_optics = localStorage.getItem('command_value');
console.log('command_optics: ', command_optics);
// clearing local storage from previous input
localStorage.clear()
// sending command inputted into form textbox
var sent_data = '(' + command_optics.toUpperCase() + ')\r\n';
var received_raw_data;
// sending data over COM port
port.write(sent_data, function(err){
if(err){
return console.log('Error on write', err.message);
}
console.log('Port.write: ', sent_data);
}
);
}
//****RECEIVING
// receiving data from COM port
port.on('data', function(data){
// raw data passed to var received_raw_data for displaying in html
received_raw_data = data;
//trim 'C:', 'R:', 'L:' from string
// data = data.replace('CRL:','')
if(data.length > 50){
data = data.slice(2);
}
console.log('Data received (raw): ', data);
// document.getElementById('data_from_optics').textContent = data
// writing data from optics module into html
document.getElementById('data_from_optics').textContent = received_raw_data;
});
// Read data that is available but keep the stream from entering "flowing mode"
port.on('readable', function () {
console.log('Data2:', port.read());
});
});
【问题讨论】：
-
你不能在浏览器中运行
server.js，你需要一个node.js 环境。例如在终端中运行node server.js。其余的代码对我来说似乎没问题。 -
就像@Quentin 解释的你总是返回相同的网站资源，你永远不会从你的 server.js 中返回任何 Javascript。您需要做的是实现某种路由逻辑，这可能很棘手，这也是大多数人使用为您完成这一切的库的原因。例如。 Express 或 KOA.. 等
-
@VladimirJovanović 我正在从 cmd 运行 server.js，除非你的意思不同。
-
谁投了反对票，你能解释一下原因吗？
标签： javascript node.js script-tag node-serialport