javascript console.log 在 CasperJS 中不起作用，使用 setTimeout 进行评估
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console.log doesn't work in CasperJS' evaluate with setTimeout
提问by Rustem
Why when I use console.login evaluate, it works:
为什么当我使用console.login 时evaluate，它有效：
casper.then(function() {
this.evaluate( function() {
console.log('hello');
});
});
But this doesn't work:
但这不起作用：
casper.then(function() {
this.evaluate( function() {
setTimeout( function() {console.log('hello');}, 1000);
});
});
回答by NiKo
Because you're mixing up casperjs and remote page environments. The evaluatefunction will execute code within the remote page env, so the console.logcall won't output anything.
因为您正在混淆 casperjs 和远程页面环境。该evaluate函数将在远程页面环境中执行代码，因此console.log调用不会输出任何内容。
If you want to catch remoteconsole.logcalls, listen to the remote.messageevent:
如果要捕获远程console.log调用，请收听remote.message事件：
casper.on('remote.message', function(msg) {
this.echo('remote message caught: ' + msg);
})
Btw, documentation for eventsis pretty much exhaustive, as well as the one for evaluate.
回答by odigity
@NiKo's answer is critical.
@NiKo 的回答很关键。
I would also suggest adding the following, since if there's an error, you might not even make it far enough to print out a console.log() msg, and instead end up with silence.
我还建议添加以下内容，因为如果出现错误，您甚至可能无法打印出 console.log() msg，而最终会保持沉默。
casper.on( 'page.error', function (msg, trace) {
this.echo( 'Error: ' + msg, 'ERROR' );
});
回答by pius
CasperJS includes ClientUtils, which can be used from the remote page to easily log to the console of the casper script:
CasperJS 包括ClientUtils，可以从远程页面使用它轻松登录到 casper 脚本的控制台：
__utils__.echo('This message is logged from the remote page to the CasperJS console');
回答by c24w
Building on @odigity's answer, this makes casperjs die with a more familiar error/stacktrace:
以@odigity 的回答为基础，这使得 casperjs 因更熟悉的错误/堆栈跟踪而死亡：
var util = require('util');
casper.on('page.error', function exitWithError(msg, stack) {
stack = stack.reduce(function (accum, frame) {
return accum + util.format('\tat %s (%s:%d)\n',
frame.function || '<anonymous>',
frame.file,
frame.line
);
}, '');
this.die(['Client-side error', msg, stack].join('\n'), 1);
});
