Develop Reference

One function for many buttons

I have dynamically created elements on the page, a picture and three buttons which are created upon clicking the main button.
All of this works, but now I am trying to change the display on the dynamically created div with the pics to "none".
More than one issue arises here for me, first I cannot find out how to make the div "images" the target, or select it.
I am trying to get one function to do this for all the elements, they are all structured equally just the pictures are different.
function hidePic(arrayPos){
var elem = document.getElementsByClassName("closingButton") + "[" + arrayPos + "]",
finalTarget = elem.getElementsByClassName("images")[0];
finalTarget.style.display = "none";
}
document.getElementsByClassName("closingButton")[0].addEventListener("click", function(){
hidePic(0);
});
This is the relevant code, lines 4 to 10. If this is commented out, the rest of the code works, but as it is I get entirely unrelated errors in dev Tools.
Click this link to see Codepen.
So the question is, how can I best implement the above code?

So just working on the code above you can do this in order to make it work for all instances. First let me point out that this:
var elem = document.getElementsByClassName("closingButton") + "[" + arrayPos + "]";
will never work. That line is building a string. What you really want to make that line work is:
var elem = document.getElementsByClassName("closingButton")[arrayPos];
But even that I find unnecessary. Take a look at this code.
function hidePic (elem) {
var finalTarget = elem.getElementsByClassName("images")[0];
finalTarget.style.display = "none";
}
var closingButtons = document.getElementsByClassName("closingButton");
var index = 0, length = closingButtons.length;
for ( ; index < length; index++) {
closingButtons[index].addEventListener("click",
function () {
hidePic(this);
}
);
}
This first finds all elements with the class closingButton. Then for each one we attach a click event listener. Instead of attempting to pass some index to this hidePic function we already have our function context which is what you seem to be trying to find in the function so lets just pass that and use it to find the image inside.
Let me know if you have any questions. I took a look at your codepen as well. I am not sure you should be forcing all that interactive HTML into a button element honestly, which itself is considered an interactive element. Not sure that meets the HTML spec. Perhaps add that HTML below the button. I bet when you click on things inside of that button it will register as clicks on the button as well unless you remove the event upon inserting your elements but then it seems like its getting too complicated for the simple stuff you are trying to do here.

The codepen complains because there is no element with the "closingButton" class, so it's trying to call addEventListener on nothing, but I'm doubting that's the actual error you're seeing.
It's also worth nothing that I think this:
var elem = document.getElementsByClassName("closingButton") + "[" + arrayPos + "]",
is excessive.
var elem = document.getElementsByClassName("closingButton")[arrayPos];
should be sufficient. Also not the syntax error at the end of the same line: it should be ; not ,. If this is the error in your code it could explain why you were getting "unrelated errors" syntax errors can cause misleading problems that are supposedly in other areas of the code!
Lastly, I'd highly recommend using JQuery to do your selection magic - it's exactly what it was designed for. If you're averse to using JS libraries, fair enough, but it would make your code a lot simpler and you can have reasonable confidence that it will perform the tasks about as optimally as is possible.

How to create a string and use a function that's named after it?

Sorry for bad wording in the question but it's hard to explain for me. I'm using several bxsliders on a page and some are placed in hidden divs. Unfortunately images are not shown in the slider after making the parent div visible unless the slider is reloaded (See here: bxSlider within show/hide divs). So let's say I initiate the sliders at the beginning with:
var slider_0=$("#slider_0 .bxslider").bxSlider({
//bxslider options here
});
var slider_4=$("#slider_4 .bxslider").bxSlider({
//bxslider options here
});
var slider_7=$("#slider_7 .bxslider").bxSlider({
//bxslider options here
});
The sliders are not consecutively numbered but there is a navigation and if I click the 7th element it leads to slider_7. So I could get the index of the clicked item with:
$(this).index();
When I call slider_7.reloadSlider(); it would work but I don't know which slider the user clicks and which number it has. So would it be possible to call that with a created string like this:
slider_name='slider_'+$(this).index();
slider_name.reloadSlider();
works not of course. Is there a way to do it?

I would create a dictionary with strings as keys and functions as values. Then, you could have O(1) lookup of the functions you're targeting.
In general, you can do it like so:
// set up your dictionary
var dictionary = {};
// add your functions
dictionary['methodName'] = function() {};
// call the functions
dictionary['methodName']();
So, for your example, you could do:
dictionary['slider_7'] = slider_7.reloadSlider;
dictionary['slider_'+$(this).index()]();

You could trigger it with
window["slider_" + $(this).index()].reloadSlider()
Although, I'm not sure whether your approach is the best. I think I'd go with arrays or with object (as a key-value pairs)

Try this:
slider_name='slider_'+$(this).index();
$("#" + slider_name + " .bx_slider").reloadSlider();

Found a working solution:
eval("slider_" + $(this).index()).reloadSlider();

Its not entirely clear here what you want/are trying to do. What it seems like you want to do is get a programmatic handle on a specific slider when a user clicks a specific part of your page. You do not accomplish this by eval()ing a string...that's what event handlers are for. So create a click event handler and in that event handler
$('#idOfWhatTheUserClicksOn').click(function(event) {
var slider = document.getElementById('#idOfRelatedSlider');
$(slider).bxSlider();
//if you need the current value of the slider you can get that too
var value = slider.value;
});
You could achieve the same with fewer LOC by using a class instead of id's with different handlers, but the concept is the same.

var slider_cache = [
$("#slider_0 .bxslider").bxSlider(),
$("#slider_1 .bxslider").bxSlider(),
$("#slider_2 .bxslider").bxSlider()
];
...
slider_cache[$(this).index()].reloadSlider();

JQuery & Javascript: Intermittant mis-matching of clicked div and returned div?

Thanks for giving this a look. I'll start with a quick image. Clicking on any of the red-boxed search results seems to return the <div> for the item directly above it.
Here I clicked on 1613 CAROUSEL CIR, but the event returned the id/content for the item representing 1612..
Sometimes it's even weirder, for example, every item following 1420 might point back to 1420. So it's not always a conflict with a <div> and it's immediate neighbor, although that's usually the case.
I've been unable to find any definite pattern in this behavior. Sometimes it's just one or two items in the list; sometimes most of the list is affected, with "a good portion" of results pointing to one particular div.
There's only one true consistency--typically the first several items work as expected, and short lists will be 100% correct. But really long lists (50+) are not necessarily worse than semi-long lists (20+).. :/
The code building the search results iterates over JSON data retrieved by a JQuery $.ajax() call, and this is the relevant code building the visible search results:
if( result.d.length > 0 )
{
var i=0;
for(i; i<result.d.length; i++)
{
// ..there's a bunch of irrelevant code here to set the map bounds..
// ..then I build the HTML using JQuery like this
//
var date = new Date();
var divID = "searchItemDiv" + date.getTime().toString();
var $searchItemDiv = $( "<div id='" + divID + "' class='searchItemDiv'>"+result.d[i].Description+"</div>" );
$searchItemDiv.data('itemData', result.d[i]);
$searchItemDiv.bind('click', onSearchItemClick);
$( "#searchResults" ).append($searchItemDiv);
}
}
While I don't suspect the event handler is the issue, the relevant code there looks like this:
function onSearchItemClick(event)
{
if( event.target.id.toString() !== '' )
{
// I clicked 1613, but event returned DIV with text of "1612"??
//
var item = $('#'+event.target.id.toString()).data('itemData');
alert( event.target.id.toString()+"\n"+
$('#'+event.target.id.toString()).text() );
// ..more irrelevant stuff to show a popup of property data..
}
}
FireFox, Chrome, and IE all demonstrate the same behavior, so it's not browser-specific.
I'm relatively sure this is not the product of a race condition during the render phase, but I'm not comfortable-enough with JavaScript to know that for certain.
I'm pretty baffled by this. FWIW, I'm a former Flex & C# developer and relatively new to JavaScript/JQuery development, so there may be a gotcha related JavaScript contexts and/or JQuery that I'm stepping into.

I would say, instead of binding the click function within a for-loop, just select all of the searchItemDiv's after the for-loop binds the data to them, and register a click function on all of them at once. You don't need a separate line to define variable i, just do it in the for statement. I also wouldn't try to generate random IDs with new Dates, that just seems unnecessary. Registering all click functionality at once will also make your click handler much simpler:
if( result.d.length > 0 )
{
for(var i = 0; i<result.d.length; i++)
{
// ..there's a bunch of irrelevant code here to set the map bounds..
// ..then I build the HTML using JQuery like this
// select the i'th searchItemDiv
$searchItemDiv = $($('.searchItemDiv')[i])
// give it the data
$searchItemDiv.data('itemData', result.d[i]);
$( "#searchResults" ).append($searchItemDiv);
}
// then register all the click handlers at once, very simple
$('.searchItemDiv').bind('click', function() {
var item = $(this);
alert(item.text());
});
}
--EDIT--
also, do the searchItemDivs already exist or are you trying to create them?
if you're trying to create them, you might want this in the for-loop instead:
for(var i = 0; i<result.d.length; i++)
{
// ..there's a bunch of irrelevant code here to set the map bounds..
// ..then I build the HTML using JQuery like this
// create a searchItemDiv
$searchItemDiv = $('<div class="searchItemDiv"></div>')
// give it the data
$searchItemDiv.data('itemData', result.d[i]);
$( "#searchResults" ).append($searchItemDiv);
}
I'm guessing that is what you want to do.

I think your problem depends on your searchItemDiv id.
Using the date doesn't ensure ids are unique so when you retrieve the object by id it will return an element (probably the first) with the same id.
Make sure to assign unique id on your elements.

Cloned row requesting same function [duplicate]

This question already exists:
Closed 10 years ago.
Possible Duplicate:
Call same function by a cloned list row
I am trying to make a simple calculation to work.
I have the following running:
http://jsfiddle.net/vSyK6/41/
Basically, the way it works now is this:
When you select an option on the drop down list it will display the content based on the option selected. Then when you select the same option again it will add, basically clone the same row.
Now, when the second option is selected "Option2" it will display an empty textbox. When you enter a number it will or should call the a function where we make a basic calculation. The function is already in the script.
However, when we have two empty textboxes it should call the same calculation function but calculate seperately and puts it in a different div. The div# where we display the amount is a called "amount"
Basically, it should work like this:
First Empty textbox -> 100 -> 100 * 22.38 = display result in div#1
Second Empty textbox -> 230 -> 230 * 22.38 = display in div#2
any idea on how to accomplish that ?

When cloning elements the id is cloned as well. It is best practice to create a new ID for the cloned elements, which will also help in accomplishing what you want. The same goes for the name attribute as well.
With a few modification to your code, http://jsfiddle.net/dNQVQ/3/, I was able to get what you were after. Let me first say that this might not be the ideal way to go, but it is a start. Like I said earlier the key is going to be setting unique ids for the cloned elements. What I did in this example was use a index as part of the list element id that is cloned with a matching index in an 'amount' div. This way when an input is updated the index is retrieved and then used to update the appropriate div. Additionally, I moved the function that did the calculation and updates to an anonymous function in the settimeout call. This makes it easy to use a reference to the updated input in the function call.

Joining the party quite late here :) Here is one vernon: http://jsfiddle.net/KVPwm/
ALso if its assignment bruv, put an assignment homework tag!
People around SO community are awesome folks so be truthful, guys will help man!
Use .on instead of live - recommendation. i.e. upgrade your JQ source if keen read this - What's wrong with the jQuery live method?
you have 2 document.ready functions also I chained few things for you.
Also think of using isNan check as well.
Rest you can read the code and play around a bit to make it more concise.
I have added 2 divs and using the id number to populate the stuff accordingly.
This should fit the cause :)
code
$("document").ready(function() {
/////////////////////////////////CALUCATIONS/////////////////////////////////
//setup before functions
var typingTimer; //timer identifier
var doneTypingInterval = 0; //time in ms, 5 second for example
$('input[name=Input2], input[name=Input1]').live('keyup', function() {
var str = $(this).prop("id");
var pattern = /[0-9]+/g;
var matches = str.match(pattern);
amount = parseFloat($(this).val()) * 22.38;
typingTimer = setTimeout(doneTyping(matches), doneTypingInterval);
});
$('#Input2').keydown(function() {
clearTimeout(typingTimer);
});
function doneTyping(matches) {
$('#amount'+matches).text(amount.toFixed(2) + " lbs");
}
$("#List-Option1,#List-Option2").hide();
$('#category').change(function() {
var str = $('#category').val();
if (str == 'Option1') {
var option1 = $("#List-Option1:first").clone().show();
$('#box li:last').after(option1);
}
if (str == 'Option2') {
var option2 = $("#List-Option2:first").clone().show();
$('#box li:last').after(option2);
}
});
});​

Unique element ID, even if element doesn't have one

I'm writing a GreaseMonkey script where I'm iterating through a bunch of elements. For each element, I need a string ID that I can use to reference that element later. The element itself doesn't have an id attribute, and I can't modify the original document to give it one (although I can make DOM changes in my script). I can't store the references in my script because when I need them, the GreaseMonkey script itself will have gone out of scope. Is there some way to get at an "internal" ID that the browser uses, for example? A Firefox-only solution is fine; a cross-browser solution that could be applied in other scenarios would be awesome.
Edit:
If the GreaseMonkey script is out of scope, how are you referencing the elements later? They GreaseMonkey script is adding events to DOM objects. I can't store the references in an array or some other similar mechanism because when the event fires, the array will be gone because the GreaseMonkey script will have gone out of scope. So the event needs some way to know about the element reference that the script had when the event was attached. And the element in question is not the one to which it is attached.
Can't you just use a custom property on the element? Yes, but the problem is on the lookup. I'd have to resort to iterating through all the elements looking for the one that has that custom property set to the desired id. That would work, sure, but in large documents it could be very time consuming. I'm looking for something where the browser can do the lookup grunt work.
Wait, can you or can you not modify the document? I can't modify the source document, but I can make DOM changes in the script. I'll clarify in the question.
Can you not use closures? Closuses did turn out to work, although I initially thought they wouldn't. See my later post.
It sounds like the answer to the question: "Is there some internal browser ID I could use?" is "No."

The answer is no, there isn't an internal id you can access. Opera and IE (maybe Safari?) support .sourceIndex (which changes if DOM does) but Firefox has nothing of this sort.
You can simulate source-index by generating Xpath to a given node or finding the index of the node from document.getElementsByTagName('*') which will always return elements in source order.
All of this requires a completely static file of course. Changes to DOM will break the lookup.
What I don't understand is how you can loose references to nodes but not to (theoretical) internal id's? Either closures and assignments work or they don't. Or am I missing something?

Closure is the way to go. This way you'll have exact reference to the element that even will survive some shuffling of DOM.
Example for those who don't know closures:
var saved_element = findThatDOMNode();
document.body.onclick = function()
{
alert(saved_element); // it's still there!
}
If you had to store it in a cookie, then I recommend computing XPath for it (e.g. walk up the DOM counting previous siblings until you find element with an ID and you'll end up with something like [#id=foo]/div[4]/p[2]/a).
XPointer is W3C's solution to that problem.

A bit confused by the wording of your question - you say that you "need a string ID that [you] can use to reference that element later, " but that you "can't store the references in [your] script because when [you] need them, the GreaseMonkey script itself will have gone out of scope."
If the script will have gone out of scope, then how are you referencing them later?!
I am going to ignore the fact that I am confused by what you are getting at and tell you that I write Greasemonkey scripts quite often and can modify the DOM elements I access to give them an ID property. This is code you can use to get a pseudo-unique value for temporary use:
var PseudoGuid = new (function() {
this.empty = "00000000-0000-0000-0000-000000000000";
this.GetNew = function() {
var fourChars = function() {
return (((1 + Math.random()) * 0x10000)|0).toString(16).substring(1).toUpperCase();
}
return (fourChars() + fourChars() + "-" + fourChars() + "-" + fourChars() + "-" + fourChars() + "-" + fourChars() + fourChars() + fourChars());
};
})();
// usage example:
var tempId = PseudoGuid.GetNew();
someDomElement.id = tempId;
That works for me, I just tested it in a Greasemonkey script myself.
UPDATE: Closures are the way to go - personally, as a hard-core JavaScript developer, I don't know how you didn't think of those immediately. :)
myDomElement; // some DOM element we want later reference to
someOtherDomElement.addEventListener("click", function(e) {
// because of the closure, here we have a reference to myDomElement
doSomething(myDomElement);
}, false);
Now, myDomElement is one of the elements you apparently, from your description, already have around (since you were thinking of adding an ID to it, or whatever).
Maybe if you post an example of what you are trying to do, it would be easier to help you, assuming this doesn't.

UPDATE: Closures are indeed the answer. So after fiddling with it some more, I figured out why closures were initially problematic and how to fix it. The tricky thing with a closure is you have to be careful when iterating through the elements not to end up with all of your closures referencing the same element. For example, this doesn't work:
for (var i = 0; i < elements.length; i++) {
var element = elements[i];
var button = document.createElement("button");
button.addEventListener("click", function(ev) {
// do something with element here
}, false)
}
But this does:
var buildListener = function(element) {
return function(ev) {
// do something with event here
};
};
for (var i = 0; i < elements.length; i++) {
var element = elements[i];
var button = document.createElement("button");
button.addEventListener("click", buildListener(element), false)
}
Anyway, I decided not to select one answer because the question had two answers: 1) No, there are no internal IDs you can use; 2) you should use closures for this. So I simply upvoted the first people to say whether there were internal IDs or who recommended generating IDs, plus anyone who mentioned closures. Thanks for the help!

If you can write to the DOM (I'm sure you can). I would solve this like this:
Have a function return or generate an ID:
//(function () {
var idCounter = new Date().getTime();
function getId( node ) {
return (node.id) ? node.id : (node.id = 'tempIdPrefix_' + idCounter++ );
}
//})();
Use this to get ID's as needed:
var n = document.getElementById('someid');
getId(n); // returns "someid"
var n = document.getElementsByTagName('div')[1];
getId(n); // returns "tempIdPrefix_1224697942198"
This way you don't need to worry about what the HTML looks like when the server hands it to you.

If you're not modifying the DOM you can get them all by indexed order:
(Prototype example)
myNodes = document.body.descendants()
alert(document.body.descendants()[1].innerHTML)
You could loop through all of the nodes and give them a unique className that you could later select easily.

You can set the id attribute to a computed value. There is a function in the prototype library that can do this for you.
http://www.prototypejs.org/api/element/identify
My favorite javascript library is jQuery. Unfortunately jQuery does not have a function like identify. However, you can still set the id attribute to a value that you generate on your own.
http://docs.jquery.com/Attributes/attr#keyfn
Here is a partial snippet from jQuery docs that sets id for divs based on the position in the page:
$(document).ready(function(){
$("div").attr("id", function (arr) {
return "div-id" + arr;
});
});

You can generate a stable, unique identifier for any given node in a DOM with the following function:
function getUniqueKeyForNode (targetNode) {
const pieces = ['doc'];
let node = targetNode;
while (node && node.parentNode) {
pieces.push(Array.prototype.indexOf.call(node.parentNode.childNodes, node));
node = node.parentNode
}
return pieces.reverse().join('/');
}
This will create identifiers such as doc/0, doc/0/0, doc/0/1, doc/0/1/0, doc/0/1/1 for a structure like this one:
<div>
<div />
<div>
<div />
<div />
</div>
</div>
There are also a few optimisations and changes you can make, for example:
In the while loop, break when that node has an attribute you know to be unique, for example #id
Not reverse() the pieces, currently it is just there to look more like the DOM structure the ID's are generated from
Not include the first piece doc if you don't need an identifier for the document node
Save the identifier on the node in some way, and reuse that value for child nodes to avoid having to traverse all the way up the tree again.
If you're writing these identifiers back to XML, use another concatenation character if the attribute you're writing is restricted.

Use mouse and/or positional properties of the element to generate a unique ID.

In javascript, you could attach a custom ID field to the node
if(node.id) {
node.myId = node.id;
} else {
node.myId = createId();
}
// store myId
It's a bit of hack, but it'll give each and every node an id you can use. Of course, document.getElementById() won't pay attention to it.

You can also use pguid (page-unique identifier) for unique identifier generation:
pguid = b9j.pguid.next() // A unique id (suitable for a DOM element)
// is generated
// Something like "b9j-pguid-20a9ff-0"
...
pguid = b9j.pguid.next() // Another unique one... "b9j-pguid-20a9ff-1"
// Build a custom generator
var sequence = new b9j.pguid.Sequence({ namespace: "frobozz" })
pguid = sequence.next() "frobozz-c861e1-0"
http://appengine.bravo9.com/b9j/documentation/pguid.html

I 'think' I've just solved a problem similar to this. However, I'm using jQuery in a browser DOM environment.
var objA = $("selector to some dom element");
var objB = $("selector to some other dom element");
if( objA[0] === objB[0]) {
//GREAT! the two objects point to exactly the same dom node
}

OK, there is no ID associated to DOM element automatically.
DOM has a hierarchycal structure of elements which is the main information.
From this perspective, you can associate data to DOM elements with jQuery or jQLite. It can solve some issues when you have to bind custom data to elements.