发送keydown事件在PhantomJS中不起作用

Question

I tried this code with a web page which its content loaded dynamically when we press keydown. (like facebook)

The goal is to get all net traffic and print it to console.

var page = require('webpage').create(),
    system = require('system'),
    address;

if (system.args.length === 1) {
    console.log('Usage: netlog.js <some URL>');
    phantom.exit(1);
} else {
    address = system.args[1];

    page.onLoadFinished      = function(req) {
        console.log('requested: ' + JSON.stiringify(req, undefined, 4));

    };
    page.open(url, function () {
        page.sendEvent('keypress', page.event.key.keydown); 
    });
    page.onResourceRequested = function (req) {
        console.log('requested: ' + JSON.stringify(req, undefined, 4));
    };

    page.onResourceReceived = function (res) {
        console.log('received: ' + JSON.stringify(res, undefined, 4));
    };


    page.open(address, function (status) {
        if (status !== 'success') {
            console.log('FAIL to load the address');
        }
        phantom.exit();
    });

}

Answer 1

First of all, PhantomJS is asynchronous. You're opening two pages at the same time. When the second page.open() the loading of the first page is aborted. This means that your page.sendEvent() call is never executed.

If you want to see whether the event is doing something, you need to let the page load and after doing some action wait a little to see if there are requests:

if (system.args.length === 1) {
    console.log('Usage: netlog.js <some URL>');
    phantom.exit(1);
} else {
    address = system.args[1];

    page.onResourceRequested = function (req) {
        console.log('requested: ' + JSON.stringify(req, undefined, 4));
    };

    page.onResourceReceived = function (res) {
        console.log('received: ' + JSON.stringify(res, undefined, 4));
    };


    page.open(address, function (status) {
        if (status !== 'success') {
            console.log('FAIL to load the address');
            phantom.exit(1);
        }

        page.sendEvent('keypress', page.event.key.keydown); 

        setTimeout(function(){
            phantom.exit();
        }, 1000);
    });
}