[英]Phantom.js callback Reference errors when refactoring Phantom.js on Node.js/Express.js to avoid “callback hell”
I have this crazy large block of code that functions, but which I am hoping to refactor properly. 我有这个疯狂的大功能代码块,但是我希望可以正确地重构它。 With accordance to Callback Hell , I tried to break it down into non-anonymous functions and seperate those functions from the central code.
根据Callback Hell ,我试图将其分解为非匿名函数,并将这些函数与中央代码分开。
However, I am running into the problem that a lot of the different sections of the code are dependent on using the others as parameters. 但是,我遇到了一个问题,代码的许多不同部分都依赖于将其他部分用作参数。 The first error message I received in the sequence is
ReferenceError: page is not defined
我在序列中收到的第一条错误消息是
ReferenceError: page is not defined
The un-refactored code is: 未重构的代码是:
function startMyFunction(firstLayerUrl) {
phantom.create(function (ph) {
ph.createPage(function (page) {
var main_file=firstLayerUrl
page.open(main_file, function (status) {
var linkArray=[];
page.evaluate(function (linkArray) {
for (var i=0; i < document.getElementsByTagName('a').length; i++) {
linkArray.push(document.getElementsByTagName('a')[i].href)
}
return linkArray;
}
, function finished(result) {
linkArray = result;
runEmailLoop(linkArray);
page.close()
ph.exit();
},linkArray);
});
});
}, {
dnodeOpts: {
weak: false
}
});
}
The attempted refactored code is: 尝试的重构代码为:
function runFirstLayer(firstLayerUrl) {
phantom.create(function (ph) {
ph.createPage(function (page) {
var main_file=firstLayerUrl
page.open(main_file, openIndexPage(status));
});
}, {
dnodeOpts: {
weak: false
}
});
}
function openIndexPage (status) {
var linkArray=[];
page.evaluate(evaluatePage(linkArray), finished(result),linkArray);
}
function evaluatePage(linkArray) {
for (var i=0; i < document.getElementsByTagName('a').length; i++) {
linkArray.push(document.getElementsByTagName('a')[i].href)
}
return linkArray;
}
function finished(result) {
linkArray = result;
runEmailLoop(linkArray);
page.close()
ph.exit();
}
How can I pass the various dependencies on, such as page
, status
, since I have tried passing page but then get another error ReferenceError: document is not defined
如何传递各种依赖项,例如
page
, status
,因为我尝试传递页面,但是又遇到另一个错误ReferenceError: document is not defined
You need to pass the functions, not call them: 您需要传递函数,而不是调用它们:
page.open(main_file, openIndexPage);
/* instead of
page.open(main_file, openIndexPage(status));
*/
and 和
page.evaluate(evaluatePage, finished, linkArray);
/* instead of
page.evaluate(evaluatePage(linkArray), finished(result),linkArray);
*/
There are no status
, linkArray
, or result
values in your code - they are parameters of the function definitions. 您的代码中没有
status
, linkArray
或result
值-它们是函数定义的参数 。
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