I have a SPA (built on webpack, with babel, etc) that includes a polyfill in the index.html:
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=Promise,Array.prototype.includes,Element.prototype.remove"></script>
One use-case for the polyfill is in order to use the Promise API on IE 10-11.
My error monitoring reporting an error on an IE 11 client of the following:
ReferenceError: 'Promise' is undefined
So I assume that particular session failed to download the polyfill for some reason.
My question is: How should I deal with this case? Is it a scenario I should expect to happen sometimes? Is the user expected to noticed the application not working properly, and reload the page?
There is an error event you can attach to allow for more control if you are really worried. You don't usually need to handle this explicitly though.
In this particular case you could migrate towards using babel to build a bundle with polyfills included in your scripts. This adds an additional build step to your process though.
Since you mentioned you're using webpack, it would just be best to include the necessary polyfills directly in the project via an import statement (something like core.js) rather than using a cdn - polyfill.io.
However, you could alternatively add an ID to the script element and listen to the onload and onerror events to determine whether the script (un)successfully loaded like so:
<script id="polyfillScript" src="https://cdn.polyfill.io/v2/polyfill.min.js?features=Promise,Array.prototype.includes,Element.prototype.remove"></script>
In your project index.js:
document.getElementById('polyfillScript').addEventListener('error', () => {
alert('Failed to load polyfill!');
});
Related
In my project, there is a custom third-party library (a single build file), which they have created using a couple of non-AMD and AMD files. And most of the properties are exposed directly to window objects. In our project as per the new requirement, we have to load this third-party library in asynchronous mode using requireJS. I tried with shim configuration but am getting an error from third party library saying that globals/window, globals/documents are needed.
How to resolve the above error in the current project without editing a third-party library? is it possible?
How to consume this third party libs properties in the project, since all properties are exposed directly to window Object.
This is the error we are encountering now
Could anyone please help me with this?
Thanks in Advance!
It looks like your 3rd party library is video.js. Video.js was (see below) creating two global objects global/window and global/document which seem to be used for testing video.js on the server where there is no window or document.
You can see their definition here and then the import. If you're willing to edit the file (and stop video.js tests from working server-side) then that's a simple solution.
You said you didn't want to edit the library though, so let's look for other solutions. You could just go ahead and define them like so:
define('global/window', [], () => {
return window;
});
define('global/document', ['global/window'], (window) => {
return window.document;
});
Then load video.js:
require(['video.7.5.0.min.js'], (videojs) => {
window.videojs = videojs;
// any other initialization you want here
});
Also it might be helpful to know which version of video.js you're using. It appears this might have been fixed in 7.11.1 (in this PR) so there's a good chance that just upgrading to that version or later makes the problem go away.
There's a lot more discussion on this problem in this issue, but it appears to be closed due to the previously mentioned PR.
Yet another attempt to marry Polymer with ES6 classes.
And it almost works except a wct test failing randomly on a polymer component with an imported es6 class (by systemjs). As far as I understand, this happens because the script, containing class definition, gets loaded after mocha executed the test. The polymer component consists of two parts - html and javascript (to compile latter to es5),
html:
<dom-module id="my-test">
<template>hello</template>
<script>
System.import('elements/my-test.js');
</script>
</dom-module>
javascript:
import {User} from 'elements/model/user.js';
Polymer({
is: "my-test",
method: function(){
console.log("method, user="+this.val);
},
ready: function(){
this.user= new User(); //this.user is randomly undefined
}
});
This seems to work quite stable in the browser, at least when loaded from localhost. But the only thing which ‘fixes’ the test is delaying Polymer’s ready call:
Polymer.whenReady = function (f) {
console.log("polymer ready");
setTimeout(f, 100);// "fix"
//f();
}
which means at some point all this will fail in browser too (maybe when serving not from the localhost).
I’m thinking about getting somehow to the system-register’s promises and making something similar to HTMLImports.whenDocumentReady, but I still don’t have clear understanding of how all this works.
So any ideas and suggestions are highly appreciated!
The sample app is on github:
git clone https://github.com/bushuyev/test_test.git
cd test_test
git checkout tags/random_fail
npm install
bower install
gulp wct
To make it succeed more often than fail - change verbose to true in wct.conf.js.
kind of update: How to import system js SFX library
It's possible to use Polymer, SystemJS and TypeScript (like ES6 but with added Polymer-friendly syntax) together in a very nice way, also handling HTML imports using SystemJS. That does involve a timing issue, and I've published a small shim that first waits from webcomponents.js to load and catches its ready event (before other code gets a chance to see it), then it loads Polymer and finally all other components and TypeScript code. Then it dispatches the event again so Polymer finishes initializing itself.
Here's an article about combining the technologies with the mentioned solution, downloadable code and a demo.
I'm working on a framework-like structure that uses curl.js as script loader. Modules can be located in either the App or Core directory, which allows me to override Core modules easily from the app. I had a server-side script to search these directories and return the first found file but then I decided that the client-side should be able to work without any help from backend, so now I have a function that tries listed directories until one of them has a file.
After a while I realized that I don't have any way to differentiate between 404 errors and syntax errors. I want the loader to fail if there is an actual error in code but in case of 404 it should just look for the next file and finally fail if no file can be found.
So, is it possible to detect if a script failed(in curl.js, AMD or generally in js) due to 404 and not because of errors in the loaded code?
Because of security concerns, browsers don't provide much information when scripts fail. In fact, IE refuses to even call the "load" event at all. The only information an AMD loader has is whether the define() was called or not.
There might be a way to detect some types of script errors, if you place your own global function call at the beginning of the script file. You can check if that function has been called. You can't detect SyntaxErrors that prevent parsing of the script, but you can detect other types of errors.
It might be possible to return the exact error to the errback function ( curl([]).then(callback, errback)) when the error happens while executing the factory function. Have you verified if this works or not?
I'm building an Ember application which started using the ember-skeleton (which means I'm using Rake Pipeline as my build toolchain). I'm using ember-i18n, and that constantly throws warnings about not having the CLDR.pluralForm function.
I've added the CLDR plural functions which ember-i18n uses to the app/vendor/ directory and added that file to my Assetfile. I've verified that the code is included in my app.js before the ember-i18n code. I've also added the appropriate require lines in my main.js:
require('plurals');
require('ember-i18n');
Still, ember-i18n is giving warnings. This is the code where it's happening:
if (typeof CLDR !== "undefined" && CLDR !== null) {
pluralForm = CLDR.pluralForm;
}
if (pluralForm == null) {
Ember.Logger.warn("CLDR.pluralForm not found. Em.I18n will not support count-based inflection.");
}
How do I make sure CLDR is defined in my app?
Because no-one else has, I will suggest a few things I might look at if I were debugging the problem myself.
If the message you see in your site is the same as in the fiddler, it is due to the files just load out of order. Pretty much "plural" must load before the "i18n" plugin. If you flip the order of the linked files it will work (I forked the error-ing example).
I would try validating I am wrong by throwing some debugger; statements into each file to see which actually gets loaded first on the browser.
Because of your require('plurals') I am going to assume you are using requirejs (github is down for maintenance so I can't actually examine ember-skeleton at the moment... so this might get an edit in the future). If this assertion is true, you need to declare that 'plurals' is a dependency of 'i18n'.
"If you do not express the dependencies, you will likely get loading errors since RequireJS loads scripts asynchronously and out of order for speed." - RequireJS API
This means you probably will end up wrapping the two calls into one, adding a define or making a "shim"; these (and more) examples can be found on the RequireJS site.
Sorry if this does not help you but without seeing it actually broken; it is hard for me to debug the problem.
EDIT: Looking at the ember-skeleton, I don't see requireJS. I have never used rake (we ended up writing our pipeline in nodeJS) so I am not quite sure if you were actually trying to concat the files with require "blaw" in rake or if you actually trying to use both.... So now I assume this answer might not be super helpful.
I’m currently testing various asynchronous-resource-loaders to see which one I want to use. At the moment Curl is throwing a ‘Promise already completed’ error…and their documentation says ‘this should never happen’.
I “suspect” I must to use a ‘define’ within each file being loaded (hope not). Further, their documentation says Curl can work with non-AMD javascript files. But...I am new to AMD and since Curl is far-faster than the other ones I'm testing...I am willing to put some time into understanding this better.
Lastly...
Even though FireBug shows the errors...all the files STILL LOAD asynchronously! But, BECAUSE there are errors...the 'then' portion of the code never gets called.
So My Questions Are:
Do I have to update all the JavaScript file-objects to be contained in a 'define'? (...hope not)
Can you see any other problem syntactically?
The Head’s Code Looks Like This:
<script type="text/javascript">
///<summary>Configuration</summary>
curl = { baseUrl: 'Includes/JavaScript/' };
</script>
<script src="Loaders/Curl/curl.js" type="text/javascript"></script>
<script type="text/javascript">
function onSuccess() {
}
function onError(ex) {
//alert(ex);
}
require(["MooTools/Core/mootools-1.2.2-core-jm",
"MooTools/mGeneral",
"jQuery/Core/jquery-1.3.2",
"jQuery/Core/jquery.tools.min",
"jQuery/ThirdPartyPlugIns/jquery.tmpl"])
.then(onSuccess, onError);
//require(["jQuery/TopUp/top_up-min"], null);
require(["jQuery/ThirdPartyPlugIns/jquery.dimensions",
"jQuery/ThirdPartyPlugIns/jQuery.Color.Animations",
"jQuery/ThirdPartyPlugIns/jquery.corners.min",
"jQuery/ThirdPartyPlugIns/jquery.tipsy",
"jQuery/ThirdPartyPlugIns/jquery.numberformatter-1.1.0",
"jQuery/ThirdPartyPlugIns/jquery.tipsy"]);
require(["general",
"WindowCenter",
"ThirdPartyPlugin/KeyBoardCapture",
"ThirdPartyPlugin/bsn.AutoSuggest_2.1.3",
"ee/8Ball",
"ee/EE"]);
</script>
Again...I'm sure it is caused by inexperience with AMD-styled code, but I still need help...so any is appreciated.
Typically, you should wrap your modules in a define() or append a define() at the end of the file if those modules have no dependencies. It seems, though, that those modules all depend on jQuery, if not other modules/files.
Since you're not using standard AMD require()/define() protocol, AMD is not really helping you with these modules. Unless you plan to write your own modules using define(), then you could use just about any async loader.
That said, there is a way to make curl.js work with non-AMD modules/files. Use the js! plugin. Here's your first block of files translated to use the js! plugin (note I also added the ".js" ext back on which I like to do with non-modules):
// we load the core files first, then get the next block that depends on them
curl([
"js!MooTools/Core/mootools-1.2.2-core-jm.js",
"js!jQuery/Core/jquery-1.3.2.js"
]).next([
"js!MooTools/mGeneral.js",
"js!jQuery/Core/jquery.tools.min.js",
"js!jQuery/ThirdPartyPlugIns/jquery.tmpl.js"
]).then(onSuccess, onError);
If any of those files within each array depend on each other, you can also use the !order suffix on them to ensure they wait for other files before executing/evaluating (be sure you're setting proper cache headers, though). Actually, the !order suffix is the fastest method as long as there are no caching issues (mobile browsers add some additional constraints on file size).
Were there any other error messages? Specifically, I would expect curl.js to throw at least one error besides just "Promise not completed".
Also, please check the Net tab (Firebug) or the Network tab (Chrome) to check that curl.js is looking in the correct location for the modules.
FWIW, I am planning to remove the alias require --> curl. The reason is that the global require function is non-standard (and explicitly not standardized in the AMD proposal). I suggest you use curl() instead of require().
curl.js also allows it's top-level api to be aliased explicitly via the "apiName" config param if you really, really want to use the name "require". :)
<script>curl = { apiName: "require" }; </script>
<script src="path/to/curl.js"></script>
<script>require(["some/modules"]).then(success, failure);</script>
More FWIW: the standard require is typically only needed in a module and can be requested by including it as a dependency:
define(["require"], function (require) {
require(["another/module"], function (another) {
// use another module here
});
});
-- John
If you're only doing normal javascript file loading (not modules), as it appears, i would encourage you to check out LABjs (http://labjs.com). LABjs focuses on being the most performance optimized loading solution (to the exclusion of some other features like module/dependency style stuff).
In fact, LABjs 2.0a (https://github.com/getify/LABjs/blob/master/next/LAB.src.js), which will be fully released in the next few days, is really exceptionally fast (even more than 1.2) at loading general scripts in parallel. I encourage you to give it a try, unless (as John eludes to above) you plan to go to module syntax... then stick with Curl or RequireJS.