javascript - Strange node.js error: TypeError: Object #<Object> has no method 'on' - Stack Overflo

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I'm trying to run a simple screen scraping app in node.js. The code is posted here: /

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?

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.onIning (http.js:1078:12)
    at HTTPParser.onHeadersComplete (http.js:87:31)

The function that appears to be throwing the error is:

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('pleted', function(){
            res.end();
        });
        rediff.search(escape(req.params.query));

    });
}

UPDATE

Now I noticed that on the first request, I get this:

SyntaxError: Unexpected strict mode reserved word
    at Module._pile (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._pile (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)

I'm trying to run a simple screen scraping app in node.js. The code is posted here: https://github./anismiles/jsdom-based-screen-scraper http://anismiles.wordpress./2010/11/29/node-js-and-jquery-to-scrape-websites/

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?

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.onIning (http.js:1078:12)
    at HTTPParser.onHeadersComplete (http.js:87:31)

The function that appears to be throwing the error is:

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('pleted', function(){
            res.end();
        });
        rediff.search(escape(req.params.query));

    });
}

UPDATE

Now I noticed that on the first request, I get this:

SyntaxError: Unexpected strict mode reserved word
    at Module._pile (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._pile (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)

• javascript
• node.js
• screen-scraping
• node.js-connect

Share Improve this question Follow edited May 25, 2023 at 16:08 aynber 23k99 gold badges5454 silver badges6767 bronze badges asked Mar 3, 2011 at 20:46 AvishaiAvishai 4,76055 gold badges4545 silver badges6767 bronze badges

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 3

The only explanation that es to mind is that the required module is not an EventEmmiter instance. Therefore, it does not have an 'on' method.

Fundamental reason behind this bug should be something to do with the EventEmittter. Allow me to explain,

1. searcher.js inherits from EventEmitter (Line-26) Searcher.prototype = new process.EventEmitter;

2. searcher-rediff.js, searcher-flipkart.js and searcher-landmarkonthenet.js extend from searcher.js, so they also inherit from EventEmitter.

3. ‘on’ method is actually defined in EventEmitter.

So, I think, for some reason, searcher.js is not able to inherit from EventEmitter and hence the method ‘on’ is missing.

You are trying to setup a listener on a module instead of an EventEmitter.

require('./searcher-rediff'); returns a Javascript module. I imagine there is actually an object in the searcher-rediff module that is the EventEmitter you are looking for.

Look through the searcher-rediff.js code to see where an EventEmitter is defined and exported, then you'll need to reference that.

In the end you'll probably end up with something like...

 var rediff = require('./searcher-rediff').searcher;

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