How can I check if a riot tag has already been loaded and compiled (in-browser with script tag), in order to avoid doing it again, programmatically.
In other words, what should I use instead of doesTagExist function in my simplified code, below?
if (!doesTagExist('my-tag')) {
riot.compile('/path/to/my-tag', function() {
riot.mount('dom-node', 'my-tag');
});
} else {
riot.mount('dom-node', 'my-tag');
}
had same problem. After bit of research I think you can't get it directly. Implementation is stored inside __TAG_IMPL which is not accessible from outside. You can however access selector for all implemented tags via riot.util.tags.selectTags(), which returns comma separated list of selectors i.e. datepicker,[data-is="datepicker"].
Oneliner for convenience
riot.util.tags.selectTags().search(/(^|,)my-tag($|,)/g) >= 0
or depending on your purity inclination
riot.util.tags.selectTags().search('"my-tag"')
Note, that first version is future-proof, if riot decides to start using single commas in selector.
Related
I'm using this with BundleTransformer from nuget and System.Web.Optimisation in an ASP.Net app. According to various docs this minifier is supposed to "remove unreachable code". I know it's not as aggressive as google closure (which I can't use presently) but I can't get even the simplest cases to work, eg;
function foo() {
}
where foo isn't called from anywhere. I can appreciate the argument that says this might be an exported function but I can't see a way to differentiate that. All my JS code is concatenated so it would be able to say for sure whether that function was needed or not if I can find the right switches.
The only way I've found to omit unnecessary code is to use the debugLookupList property in the web.config for BundleTransformer but that seems like a sledgehammer to crack a nut. It's not very granular.
Does anyone have an example of how to write so-called 'unreachable code' that this minifier will recognise?
Here's a place to test online
I doubt the minifier has any way of knowing if a globally defined function can be removed safely (as it doesn't know the full scope). On the other hand it might not remove any unused functions and might only be interested in unreachable code (i.e. code after a return).
Using the JavaScript Module Pattern, your unused private functions would most likely get hoovered up correctly (although I've not tested this). In the example below, the minifier should only be confident about removing the function called privateFunction. Whether it considers unused functions as unreachable code is another matter.
var AmazingModule = (function() {
var module = {};
function privateFunction() {
// ..
}
module.otherFunction = function() {
// ..
};
return module;
}());
function anotherFunction() {
// ..
}
I want to understand in which case I should or have to use the evaluate function.
I have read the API doc about the evaluate function of CasperJS, but I'm unsure in which case I should use this function. And what does DOM context mean? Can somebody provide an example?
The CasperJS documentation has a pretty good description of what casper.evaluate() does.
To recap: You pass a function that will be executed in the DOM context (you can also call it the page context). You can pass some primitives as arguments to this function and return one primitive back. Keep in mind that this function that you pass to evaluate must be self contained. It cannot use variables or functions that are defined outside of this function.
CasperJS provides many good functions for everyday tasks, but you may run into a situation when you need a custom function to do something. evaluate is basically there to do
Retrieve some value from the page to take action based on it in your script
Manipulate the page in some way other than clicking or filling out a form
Combinations of points 1. and 2.
Examples
You may need a generic function to get the checked property from a checkbox. CasperJS currently only provides getElementAttribute function which will not work in this case.
function getChecked(cssSelector){
return document.querySelector(cssSelector).checked;
}
if (casper.evaluate(getChecked, selector)){
// do something
} else {
// do something else
}
In most of the cases it is just preference of what you want to use. If you have a list of users with data-uid on each li element then you have at least 2 possibilities to retrieve the uids.
Casper-only:
var uids = casper.getElementsAttribute('ul#user-list > li', 'data-uid');
Casper-Evaluate:
var uids = casper.evaluate(function(){
return Array.prototype.map.call(document.querySelectorAll('ul#user-list > li'), function(li){ return li["data-uid"]});
});
Regarding manipulation everything is possible but depends on what you want to do. Let's say you want to take screenshots of web pages, but there are some elements that you don't want to be there. Or you could add your own CSS to the document.
Remove elements:
function removeSelector(cssSelector){
var elements = document.querySelectorAll(cssSelector);
Array.prototype.forEach.call(elements, function(el){
el.parent.removeChild(el);
});
}
casper.evaluate(removeSelector, '.ad'); // if it would be that easy :)
Change site appearance through CSS:
function applyCSS(yourCss){
var style = document.createElement("style");
style.innerHTML = yourCss;
document.head.appendChild(style);
}
casper.evaluate(applyCSS, 'body { background-color: black; }'); // non-sense
Roots
CasperJS is built on top of PhantomJS and as such inherits some of its quirks. The PhantomJS documentation for page.evaluate() says this:
Note: The arguments and the return value to the evaluate function must be a simple primitive object. The rule of thumb: if it can be serialized via JSON, then it is fine.
Closures, functions, DOM nodes, etc. will not work!
Custom parameters in a CDE/CTools dashboard are great for defaulting initial values of parameters, e.g. setting a date parameter to today. i.e. the parameter looks like:
function() {
// some code
return val
}
However there is an issue with them. The first time you access a "custom parameter" in code, it is a function not a string. So you have to use:
paramName()
To get its value.
Once the end user selects a value then you have to use
paramName
This is really awkward in complicated dashboards with lots of prompts. Is there a better way this can be done? (Perhaps there is something in javascript I'm missing to help here?)
OK, there is a solution, but I dont like it!
First; Move all the init code into named procedures e.g.
function monthInit() {
return "june";
}
Then in the custom parameter for month, just say:
monthInit();
That way the custom parameter is always a string, and never starts off as a function.
Not ideal though because then all your init code is in a separate bit of js.
I'd like to use UUID as action parameters. However, unless I use .toString() on the UUID objects when generating the action URL's, Play seems to serialize the object differently; Something like this: referenceId.sequence=-1&referenceId.hashCode=1728064460&referenceId.version=-1&referenceId.variant=-1&referenceId.timestamp=-1&referenceId.node=-1
However, using toString "works", but when I redirect from one action to another by simply invoking the method directly, there's no way I can call toString, as the method expects a UUID. Therefore it gives me the representation shown above.
Is there any way I can intersect the serialization of a certain type?
aren't you able to just use string in your action parameter? you know that this string is an UUID, so you can always recreate UUID from it. Maybe this is not the solution for you but that's my first thought. As far as I know play serializes objects like that when passing them trough paremeters.
If this does not work for you try finding something here: http://www.playframework.org/documentation/1.2.4/controllers
I found a way to do this, but right now it means hacking a part of the frameworks code itself.
What you basically need is a TypeBinder for binding the value from the String to the UUID
and a small code change in
play/framework/src/play/data/binding/Unbinder.java
if (!isAsAnnotation) {
// We want to use that one so when redirecting it looks ok. We could as well use the DateBinder.ISO8601 but the url looks terrible
if (Calendar.class.isAssignableFrom(src.getClass())) {
result.put(name, new SimpleDateFormat(I18N.getDateFormat()).format(((Calendar) src).getTime()));
} else {
result.put(name, new SimpleDateFormat(I18N.getDateFormat()).format((Date) src));
}
}
}
//here's the changed code
else if (UUID.class.isAssignableFrom(src.getClass()))
{
result.put(name, src.toString());
}
else {
// this code is responsible for the behavior you're seeing right now
Field[] fields = src.getClass().getDeclaredFields();
for (Field field : fields) {
if ((field.getModifiers() & BeanWrapper.notwritableField) != 0) {
// skip fields that cannot be bound by BeanWrapper
continue;
}
I'm working with the framework authors on a fix for this. will come back later with results.
if you need this urgently, apply the change to the code yourself and rebuild the framework by issuing
ant
in the playframework/framework
directory.
function getPerformActionFunction(someParameter) {
return function() {
performAction(someParameter);
}
}
What would you call getPerformActionFunction to indicate that it doesn't perform the action, but rather returns a function which performs the action?
Example is Javascript, and if there's a Javascript convention that's preferred, but also interested in other languages if the answer differs.
Not sure if it's in any style guides, but I quite like the -er suffix to suggest something that is able to do an action.
e.g. getActionPerformer or fooHandler or XMLTransformer
I've used this sort of style in C#, Java and Clojure an it seems to work OK.