I apologize if this is a duplicate, just haven't been able to find anything close to this myself.
The company I work for has an online reporting system that is run by an ng-app applied directly to the body tag. I have been tasked with modifying the result that returns from this ng-app. Following code is called using onload attached to the body tag.
function getElements(){
var list;
list = document.getElementsByClassName("neutral");
[].forEach.call(list, function (listItem) {
addNeutral(listItem);
});
...
Basically, trying to find anything with class "neutral" and apply results from another function to it. The addNeutral function is basically just
element.classList.add("neutralHighlight");
This code seems to run and gathers the correct list of elements, but the new class is never added and no errors occur. So long story short, is there any way to modify the output of a ng-app using code separate from the ng-app itself? Any guidance would be greatly appreciated.
Update 3/5/20
So I implemented Shaun's response and it still isn't working properly. With some debug messages, I can see that it collects the "list" variable as an HTMLCollection. The forEach function doesn't seem to even trig
function getElements(){
var list;
list = document.getElementsByClassName("neutral");
console.log(list); //Debug - Shows in console
[].forEach.call(list, function (listItem) {
console.log(listItem); //Debug - Does not show in console
addNeutral(listItem);
});
}
function addNeutral(element){
angular.element(element).addClass("neutralHighlight");
console.log("!!!end addNeutral"); //Debug - Does not show in console
}
Update 3/9/20 -SOLUTION-
Application is returning the HTML Collection, but it displays with a length of 0 (still displays the objects, but I think that's a Firefox console thing). When trying to loop through the list items, it returns null for the first item, so the function is still being called before the Angular app loads completely.
That being said, I messed around with things a bit this morning and came to a solution! I ended up using the setInterval function with a 5 second interval (since I need it to update, I may change this to optimize it later by adding onChange items to the objects I grab initially). The setTimeout that was proposed would have worked with a delay added to it. This probably isn't the most elegant solution, and there's probably a better way to do it, but this works for anyone interested.
function getElements(){
var list;
list = document.getElementsByClassName("neutral");
for (i = 0; i <= list.length; i++){
var listItem = list.item(i);
addNeutral(listItem);
}
}
function loadFunction(){
setInterval(function(){getElements()}, 5000);
}
I added <script>loadFunction()</script> right before the closing HTML tag to execute.
Update 4/21/20 -IMPROVED SOLUTION- CSS Attributes
So this is a bit specific to my scenario, but I wanted to include it for anybody else who may come across this in the future. I was actually able to accomplish this entirely with CSS attribute selectors. The tags that I wanted to edit all had specific titles assigned to them via the ng-app provided from the company, so I was able to use CSS selectors like div [title~="NotReadyForNextCall"]{<custom styling here>} to select any block that included an agent who was not ready for their next call. This is a much better solution in terms of resources required to operate and overall performance, so I hope it helps anybody looking at this down the line!
You might be able to get around this by using the angular object in your code and adding the class on an angular.element instead. AngularJS doesn't use a virtual DOM but it does use its own node references (which is what makes it so tricky to work with outside of the framework, as Lex pointed out in the comments of your question). Try:
angular.element(element).addClass("neutralHighlight");
Yes, you have access to angular outside of the app! And a last note, addClass() is available on angular.element because AngularJS comes with jqLite.
Further investigation
It looks like the above solution works if the class 'neutral' is being added in angular via the class attribute, but it looks like your app may be adding it programmatically with the ng-class directive after the DOM has rendered.
I wrapped your getElements() function in a setTimeout():
setTimeout(getElements);
This is unfortunately not a guarantee that the ng-class update will have taken place, but what it does is it executes the function after the previous digest cycle has completed and that appears to be working.
An even safer solution would be to use document.ready but again with the angular.element wrapper. This will ensure the initial DOM state has been rendered by AngularJS, including applied directives:
angular.element(document).ready(function() {
getElements();
});
EDIT: Update 3/9/20 -SOLUTION-
The solution proposed in the answer is almost identical to the setTimeout() answer given here. The only difference is setInterval() will keep executing the code every 5 seconds until you tell it to stop.
You can do this with the following:
var loadFunction = setInterval(function() {
var el = getElements();
if (el) clearInterval(loadFunction);
}, 5000);
And just return a bool in your getElements() like so:
function getElements() {
var list;
var found = false;
list = document.getElementsByClassName("neutral");
[].forEach.call(list, function (listItem) {
addNeutral(listItem);
found = true;
});
return found;
}
See: codepen.io/shaunetobias/pen/KKpXRxq
Related
First, a little disclaimer: I'm no master at working with javaScript / jQuery, although I have handled it quite a few times. Recently, I have sometimes found myself being forced to make redundant code, i.e. repeat line(s) of code regarding diferent events, because I don't know how to do it in a more efficient way. A small example would be enabling a button after checking if any checkbox in a page is selected. This is done either upon page loading or after any checkbox is selected:
var checkboxes = $("input[type='checkbox']");
$('#nextfl').attr("disabled", !checkboxes.is(":checked"));
checkboxes.click(function()
{
$('#nextfl').attr("disabled", !checkboxes.is(":checked"));
});
I don't think this could be solved using the bind or on functions, for instance, since it refers to events not related to the same element. I believe it must exist a straightforward solution to this though, but as I said before, I have little experience in JS / jQ, and there are some similar situations where I have repeated dozens of lines of code, which is of course at least a bad practice.
You can always split redundant code into functions with javascript:
function doCheckboxLogic () {
$('#nextfl').attr("disabled", !checkboxes.is(":checked"));
// and any other logic that needs to be done
}
You then call that function in place of the redundant code block:
checkboxes.click(function()
{
doCheckboxLogic();
});
There's not much gained here since it's one line of code anyway, but this really helps with encapsulating more complicated blocks of logic
Best practice in this case is to extract common logic to its own function which can be called as required. Try this:
$(function() {
var $checkboxes = $("input[type='checkbox']");
function checkState() {
$('#nextfl').attr("disabled", !$checkboxes.is(":checked"));
}
$checkboxes.click(checkState); // run the function on click of a checkbox
checkState(); // run it on load of the page
});
I have been writing a reusable script, let's call it a plugin although it's not jQuery, that can be initialised in a declarative way from the HTML. I have extremely simplified it to explain my question so let's say that if a user inserts a tag like:
<span data-color="green"></span>
the script will fire because the attribute data-color is found, changing the color accordingly.
This approach proved very handy because it avoids anyone using the plugin having to initialise it imperatively in their own scripts with something like:
var elem = document.getElementsByTagName('span')[0];
myPlugin.init(elem);
Moreover by going the declarative way I could get away without defining any global (in this case myPlugin), which seemed to be a nice side effect.
I simplified this situation in an example fiddle here, and as you can see a user can avoid writing any js, leaving the configuration to the HTML.
Current situation
The plugin is wrapped in a closure like so:
;(function(){
var changeColor = {
init : function(elem){
var bg = elem.getAttribute('data-color');
elem.style.background = bg;
}
};
// the plugin itslef looks for appropriate HTML elements
var elem = document.querySelectorAll('[data-color]')[0];
// it inits itself as soon as it is evaluated at page load
changeColor.init(elem);
})();
The page loads and the span gets the correct colour, so everything is fine.
The problem
What has come up lately, though, is the need to let the user re-evaluate/re-init the plugin when he needs to.
Let's say that in the first example the HTML is changed dynamically after the page is loaded, becoming:
<span data-color="purple"></span>
With the first fiddle there's no way to re-init the plugin, so I am now testing some solutions.
Possible solutions
Exposing a global
The most obvious is exposing a global. If we go this route the fiddle becomes
http://jsfiddle.net/gleezer/089om9z5/4/
where the only real difference is removing the selection of the element, leaving it to the user:
// we remove this line
// var elem = document.querySelectorAll('[data-color]')[0];
and adding something like (again, i am simplifying for the sake of the question):
window.changeColor = changeColor;
to the above code in order to expose the init method to be called from anywhere.
Although this works I am not satisfied with it. I am really looking for an alternative solution, as I don't want to lose the ease of use of the original approach and I don't want to force anyone using the script adding a new global to their projects.
Events
One solution I have found is leveraging events. By putting something like this in the plugin body:
elem.addEventListener('init', function() {
changeColor.init(elem);
}, false);
anybody will be able to just create an event an fire it accordingly. An example in this case:
var event = new CustomEvent('init', {});
span.dispatchEvent(event);
This would re-init the plugin whenever needed. A working fiddle is to be found here:
http://jsfiddle.net/gleezer/tgztjdzL/1/
The question (finally)
My question is: is there a cleaner/better way of handling this?
How can i let people using this plugin without the need of a global or having to initialise the script themselves the first time? Is event the best way or am I missing some more obvious/better solutions?
You can override Element.setAttribute to trigger your plugin:
var oldSetAttribute = Element.prototype.setAttribute;
Element.prototype.setAttribute = function(name, value) {
oldSetAttribute.call(this, name, value);
if (name === 'data-color') {
changeColor.init(this);
}
}
Pros:
User does not have to explicitly re-initialize the plugin. It will happen automatically when required.
Cons:
This will, of course, only work if the user changes data-color attributes using setAttribute, and not if they create new DOM elements using innerHTML or via some other approach.
Modifying host object prototypes is considered bad practice by many, and for good reasons. Use at your own risk.
I want to attach a jQuery plugin function to an element on my site that exists only on one page. Currently, I'm using this conditional to prevent triggering the limiter function and throwing an error when there is no #advertiser_co_desc in view.
jQuery(document).ready(function($) {
var elem = $('#charNum');
if ($('#advertiser_co_desc').length) {
$('#advertiser_co_desc').limiter(180, elem);
}
});
On my website #advertiser_co_desc is present only on one page.
My solution does the job, but my qualm stems from the fact that the jQuery plugin code as well as the plugin function call presented above (they are both in the same file) get fetched by the browser and the condition is continuously evaluated regardless of whether a user ever gets to a page where #advertiser_co_desc exists.
Is the method I'm using optimal, or is there a better way to attach this particular JS only to the page where '#advertiser_co_desc` exists? Naturally, I wan to avoid adding my scripts in the same file with the PHP code.
Or you can wrap the plugin method as,
var _limiter = $.fn.limiter;
$.fn.limiter = function(limit, element) { // provide complete argmuments
if(this.length) {
_limiter.call(limit, element);
}
};
Make sure that plugin is loaded before this statements.
The best and optimal way to check existence of an element by jquery, is $('#advertiser_co_desc').length that you have used already. So no need to change your code.
There is probably a very simple explanation for this (and likely a much cleaner way to do it), but I'm new and can't quite figure it out. Any assistance would help the learning process...
I have one script that displays one div or another based (show instead of hide) on what a user selects from a dropdown list. Like so:
var PickDiv = (function(){
var _obj = {};
var hideShow = function(elem){
if($(elem).val() === '1'){
$("#slider_action").show();
$("#slider_dollar").hide();
}else if($(elem).val() === '2'){
$("#slider_dollar").show();
$("#slider_action").hide();
}else{
$("#slider_dollar, #slider_action").hide();
}
};
_obj.checkValue = function(){
hideShow($('#build_opt'))
};
var events = function(){
$('#build_opt').change(function(){
hideShow(this);
});
};
$(document).ready(function(){
events ();
checkValue ();
});
return _obj;
}());
This works great and displays the right div based on what is selected from the dropdown. I thought I could reuse this same idea later in my code to have the same effect. Once the div is displayed (after making a selection related to script above), I need to provide another dropdown with additional options. The user will select one of these and then a div will display. So, I figured, I could use something like this:
var RunRate = (function(){
var _obj2 = {};
var hideShow_2 = function(elem_2){
if($(elem_2).val() === '6'){
$("#db_sign").show();
$("#app_down", "#in_redem", "#site_vis", "#cont_ent" ).hide();
}else if($(elem_2).val() === '7'){
$("#app_down").show();
else{
$("#app_down", "#in_redem", "#site_vis", "#db_sign", "#cont_ent" ).hide();
}
};
_obj2.checkValue_2 = function(){
hideShow_2($('#action_type_2'))
};
var events_2 = function(){
$('#action_type_2').change(function(){
hideShow_2(this);
});
};
$(document).ready(function(){
events_2 ();
checkValue_2 ();
});
return _obj2;
}());
Of course, this doesn't work. I tried a number of different things with no luck. Note that if I exclude the first script from my code, the second script works fine, so I know it works. I'm guessing it has something to do with the two scripts sharing a variable or something about jquery that I'm clearly missing.
Any help would be appreciated. Overall, looking to be able to do a number of these types of dependent dropdowns without interfering with one another.
Thanks for your help!
UPDATE:
Note that if in the second script, I replace:
$(document).ready(function(){
with
$( window ).load(function() {
then the problem is solved. So, clearly the problem is related to the document.ready interfering with each other, but I don't know how to fix this without this "hack" above especially if I want to use more of these dependent dropdowns. Is there a way to pass a different variable and call that instead of document?
UPDATE 2
Figured out the problem...my original code was throwing an error due to an undefined reference (checkValue). That error was causing the document ready to not work in the second function. Referenced a more detailed explanation in my answer below.
Figured out the problem thanks to this answer to a related question pointed out by #skmasq. #JustinWood was onto something with his comment on my original question. Turns out that my scripts were throwing an error ("Uncaught ReferenceError: checkValue is not defined"), which was not allowing the document ready function to work properly.
Here's the critical part of the answer :
It is important to note that each jQuery() call must actually return. If an exception is thrown in one, subsequent (unrelated) calls will never be executed.
This applies regardless of syntax. You can use jQuery(), jQuery(function() {}), $(document).ready(), whatever you like, the behavior is the same. If an early one fails, subsequent blocks will never be run.
Could be that $(document).ready() overwrites the initial job? It doesn't matter if you use different functions/variable names ...$(document).ready is the same ...
I need to be able to determine when an object is created (not a DOM element -- a JavaScript object).
An answer to this question has some very useful looking code for creating observable properties, so you can have a function fire when a property changes.
In my situation I need to do something when the object/property is created, not an existing property changed, and my limited understanding of such matters did not help me figure out if or how I could use that code to do this after much squinting.
The situation is: page loads a bunch of scripts. Some of the scripts create things that are needed by other scripts, e.g:
ThisStuff = (function () {
// blah blah
return self;
} ());
Some other code needs to initialize this ThisStuff, whenever it's available, which may be after the DOM is done loading. The user doesn't actually need ThisStuff right away, so it's fine for it to happen whenever the script is done loading. So I would like to do something along lines of:
$(document).ready(function() {
wheneverIsAvailable(window,'ThisStuff', function(object) {
object.init(args);
})
});
I realize there are other solutions to this problem (changing script order, or loading scripts on demand) but those are difficult because of the architecture. So I'm only interested in a way to do this versus other solutions. If jQuery offers some such functionality, that's fine also as I'm using it.
You could have a setInterval checking a number of times a second to watch the specific variable. You can check whether it is created using obj.hasOwnProperty(prop). When it is created, you invoke the function, and clear the interval.
It might be dirty but it might also just work fine for you.
Edit: I coded this for you: http://jsfiddle.net/jhXJ2/2/. It also supports passing additional arguments to the function.
window.__intervals = [];
function wheneverIsAvailable(obj, prop, func) {
var id = (Math.random()+"").substring(2);
var args = arguments;
window.__intervals[id] = window.setInterval(function() {
if(obj.hasOwnProperty(prop)) {
window.clearInterval(window.__intervals[id]);
func(Array.prototype.slice.call(args, 3));
// Call function with additional parameters passed
// after func (from index 3 and on)
}
}, 1000/ 50);
}
wheneverIsAvailable(window, 'test', function() {
alert(arguments[0]);
}, 'Woot!');
window.setTimeout('window.test = 123', 1000);
This is a bit far-fetched but it might work.
You would need to use knockoutjs, a javascript library. It's awesome but is built for a slightly different purpose.
Anyways it has a dependentObservable thing which allows to fire up an event whenever a certain value changes. Now I know you want on creation but you can check whether your variable holds any value (other than what you provided initially), if yes then consider it initialize.
Let me know if you think this sounds feasible.