Adding a regional iteration of a library that was unable to be loaded

Question

Adding a regional iteration of a library that was unable to be loaded

Recently, I have been experimenting with PhantomJS to capture screenshots of a webpage every five minutes. While the process runs smoothly most of the time, I encountered an issue where the AngularJS library fails to load intermittently. This results in the inability to render the page correctly. To address this challenge, I am actively exploring ways to incorporate a local copy in place of the missing library. Here is what I have attempted so far...

var page = require('webpage').create(),system = require('system');
var home = 'https://smartway.tn.gov/traffic/';

page.open(home, function (status) {
    if(status === "success"){
        page.injectJs('angular.js');
        window.setTimeout((function() {
            page.evaluate(function () {
                /*stuff*/
            });
        }), 2000);
    }
});

The file angular.js serves as my offline version of the script that would typically be fetched by the site. Normally, the website imports this script along with others at the end of the body. I am presently investigating the optimal approach for its inclusion. One conjecture is that it may need to replace the respective script tag within the HTML document to ensure proper sequencing during loading. However, executing this substitution technique remains unclear to me.

I appreciate any insights or suggestions on this matter.

javascript angularjs phantomjs

Answer 1

Answer №1

When a single JavaScript file, especially one that is foundational like a framework, fails to load, it can create problems as many other scripts may depend on it. In such cases, if the core framework is not loaded successfully, scripts relying on it will cease to function due to unresolved references to angular.

One possible solution could involve injecting a local version of angular. However, this approach would require manually updating all other scripts that reference angular, either by downloading and evaluating them in order or adding them to the page as script elements. This method is not recommended as it is prone to errors.

An alternative approach would be to reload the page if angular is not detected post initial page load (within the callback of page.open). To handle potential reloading issues, this process needs to be implemented recursively:

function open(countDown, done){
    if (countDown === 0) {
        done("ERROR: not loaded");
        return;
    }
    page.open(home, function (status) {
        if(status === "success"){
            var angularExists = page.evaluate(function () {
                return !!angular;
            });
            if (angularExists){
                done();
            } else {
                open(countDown - 1, done);
            }
        } else {
            open(countDown - 1, done);
        }
    });
}
open(5, function(err){
    if(err) {
        console.log(err);
    } else {
        page.render(target);
    }
});

Another option is to utilize the page.reload() function instead of using page.open().

Alternatively, you can always inject the local version of angular at the start of the page loading process and prevent any requests for the remote script version:

page.onLoadStarted = function() {
    page.injectJs('angular.js');
};
page.onResourceRequested = function(requestData, networkRequest) {
    var match = requestData.url.match(/angular\.min\.js/g);
    if (match != null) {
        networkRequest.abort(); 
    }
};
page.open(home, function (status) {
    if(status === "success"){
        window.setTimeout((function() {
            page.evaluate(function () {
                /*stuff*/
            });
        }), 2000);
    }
});

This approach does not rely on page reloading to address the issue.

Answer 2

When a single JavaScript file, especially one that is foundational like a framework, fails to load, it can create problems as many other scripts may depend on it. In such cases, if the core framework is not loaded successfully, scripts relying on it will cease to function due to unresolved references to angular.

One possible solution could involve injecting a local version of angular. However, this approach would require manually updating all other scripts that reference angular, either by downloading and evaluating them in order or adding them to the page as script elements. This method is not recommended as it is prone to errors.

An alternative approach would be to reload the page if angular is not detected post initial page load (within the callback of page.open). To handle potential reloading issues, this process needs to be implemented recursively:

function open(countDown, done){
    if (countDown === 0) {
        done("ERROR: not loaded");
        return;
    }
    page.open(home, function (status) {
        if(status === "success"){
            var angularExists = page.evaluate(function () {
                return !!angular;
            });
            if (angularExists){
                done();
            } else {
                open(countDown - 1, done);
            }
        } else {
            open(countDown - 1, done);
        }
    });
}
open(5, function(err){
    if(err) {
        console.log(err);
    } else {
        page.render(target);
    }
});

Another option is to utilize the page.reload() function instead of using page.open().

Alternatively, you can always inject the local version of angular at the start of the page loading process and prevent any requests for the remote script version:

page.onLoadStarted = function() {
    page.injectJs('angular.js');
};
page.onResourceRequested = function(requestData, networkRequest) {
    var match = requestData.url.match(/angular\.min\.js/g);
    if (match != null) {
        networkRequest.abort(); 
    }
};
page.open(home, function (status) {
    if(status === "success"){
        window.setTimeout((function() {
            page.evaluate(function () {
                /*stuff*/
            });
        }), 2000);
    }
});

This approach does not rely on page reloading to address the issue.

Adding a regional iteration of a library that was unable to be loaded

Answer №1

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