javascript 奇怪的 node.js 错误：TypeError: Object #<Object> 没有方法“on”
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Strange node.js error: TypeError: Object #<Object> has no method 'on'
提问by Avishai
I'm trying to run a simple screen scraping app in node.js. The code is posted here: https://github.com/anismiles/jsdom-based-screen-scraperhttp://anismiles.wordpress.com/2010/11/29/node-js-and-jquery-to-scrape-websites/
我正在尝试在 node.js 中运行一个简单的屏幕抓取应用程序。代码发布在这里：https: //github.com/anismiles/jsdom-based-screen-scraper http://anismiles.wordpress.com/2010/11/29/node-js-and-jquery-to-scrape -网站/
The server starts up fine, but then when I run a query on it, I get the following error. Does anyone know why that is?
服务器启动正常，但是当我对其运行查询时，出现以下错误。有谁知道这是为什么？
TypeError: Object #<Object> has no method 'on'
at Object.<anonymous> (/Users/avishai/Downloads/anismiles-jsdom-based-screen-scraper-f0c79d3/searcher-server.js:9:10)
at param (/Users/avishai/.node_libraries/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:146:21)
at param (/Users/avishai/.node_libraries/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:157:15)
at pass (/Users/avishai/.node_libraries/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:162:10)
at Object.router [as handle] (/Users/avishai/.node_libraries/.npm/connect/0.5.10/package/lib/connect/middleware/router.js:168:6)
at next (/Users/avishai/.node_libraries/.npm/connect/0.5.10/package/lib/connect/index.js:218:15)
at Server.handle (/Users/avishai/.node_libraries/.npm/connect/0.5.10/package/lib/connect/index.js:231:3)
at Server.emit (events.js:45:17)
at HTTPParser.onIncoming (http.js:1078:12)
at HTTPParser.onHeadersComplete (http.js:87:31)
The function that appears to be throwing the error is:
似乎抛出错误的函数是：
function books(app){
app.get('/:query', function(req, res, next) {
res.writeHead(200, { 'Content-Type': 'text/html' });
var rediff = require('./searcher-rediff');
rediff.on('on_book', function(item){
res.write(item + "<br/>");
});
rediff.on('completed', function(){
res.end();
});
rediff.search(escape(req.params.query));
});
}
UPDATE
更新
Now I noticed that on the first request, I get this:
现在我注意到在第一个请求中，我得到了这个：
SyntaxError: Unexpected strict mode reserved word
at Module._compile (module.js:369:25)
at Object..js (module.js:380:10)
at Module.load (module.js:306:31)
at Function._load (module.js:272:10)
at require (module.js:318:19)
at Object.<anonymous> (/Users/avishai/Downloads/anismiles-jsdom-based-screen-scraper-f0c79d3/searcher.js:2:15)
at Module._compile (module.js:374:26)
at Object..js (module.js:380:10)
at Module.load (module.js:306:31)
at Function._load (module.js:272:10)
采纳答案by Animesh
Fundamental reason behind this bug should be something to do with EventEmittter. let me explain,
此错误背后的根本原因应该与 EventEmittter 有关。让我解释，
searcher.js inherits from EventEmitter (Line-26) Searcher.prototype = new process.EventEmitter;
searcher-rediff.js, searcher-flipkart.js and searcher-landmarkonthenet.js extend from searcher.js, so they also inherit from EventEmitter.
‘on' method is actually defined in EventEmitter.
searcher.js 继承自 EventEmitter (Line-26) Searcher.prototype = new process.EventEmitter;
searcher-rediff.js、searcher-flipkart.js 和 searcher-landmarkonthenet.js 继承自 searcher.js，因此它们也继承自 EventEmitter。
'on' 方法实际上是在 EventEmitter 中定义的。
So, i think, for some reason, searcher.js is not able to inherit from EventEmitter and hence the method ‘on' is missing.
因此，我认为，出于某种原因，searcher.js 无法从 EventEmitter 继承，因此缺少“on”方法。
回答by J. K.
The only explanation that comes to mind is that the required module is not an EventEmmiter instance. Therefore, it does not have an 'on' method.
想到的唯一解释是所需的模块不是 EventEmmiter 实例。因此，它没有“开启”方法。
回答by Chris W.
You are trying to setup a listener on a module instead of an EventEmitter.
您正在尝试在模块而不是 EventEmitter 上设置侦听器。
require('./searcher-rediff');returns a Javascript module. I imagine there is actually an object in the searcher-rediffmodule that is the EventEmitter you are looking for.
require('./searcher-rediff');返回一个 Javascript 模块。我想searcher-rediff模块中实际上有一个对象是您正在寻找的 EventEmitter。
Look through the searcher-rediff.jscode to see where an EventEmitter is defined and exported, then you'll need to reference that.
查看searcher-rediff.js代码以查看 EventEmitter 的定义和导出位置，然后您需要引用它。
In the end you'll probably end up with something like...
最后你可能会得到类似的东西......
var rediff = require('./searcher-rediff').searcher;
