Develop Reference

jquery 3.2.1 targetting elements by name is giving undefined even though they exist

Is there anything glaringly obvious that I'm missing here:
I have the following markup in an application:
<table id="regulatoryInformationTable">
<form id="searchRegulatoryInformation">
<input type="hidden" name="id" value="ID000001"/>
</form>
</table>
Using jquery 3.2.1 I'm trying to get the value of the hidden field. I've tried:
$("#searchRegulatoryInformation input[name='id']").val();
and just
$("input[name='id']").val();
There are no other elements in the document with the ID searchRegulatoryInformation or the name attribute id.
I can't understand why, but when I console.log() either of these statements it's giving me undefined
Edit - it seems the issue (see comments) is the wrapping table #regulatoryInformationTable. If I remove this, I can target things by the ID #searchRegulatoryInformation. But with the table in place, I cannot.

Struts 2 Form Bind Parameters To Collection Without Using Index

Struts Version: 2.3.16.3
Is there a way to populate a list of objects without having to specify the index? Currently I have to reference the collection like so:
<input name="myCollection[0].myProperty" value="some value" />
I really want to be able to do something like this:
<input name="myCollection[].myProperty" value="some value" />
I am dynamically adding and removing elements on the page with JavaScript and it has been a pain to get the indexing right with the JavaScript. Rather just have the backend add to the end of the collection in the order the elements come across from the form. Similar to how PHP processes it.
The docs for the parameters interceptor say that it is really just a ognl expression that the input name is binding to. I went to the ognl docs and it says you can reference array's like this:
array["length"]
which would be the next element in the array. The parameter interceptor is spitting out a message that it is rejecting this parameter name. I would really like to find a way to make this happen, even if it means extending the parameters interceptor.

Well, since
you are manipulating the page with Javascript
you are having troubles detecting / updating the index of elements when adding / removing them
the simplest solution is:
use the syntax you prefer when manipulating them, for example myCollection[].myProperty, and
convert them into the form desired by Struts in a pre-submit function.
This way you don't have to bother with the indexes while manipulating the elements, but only once, at the end, when you can simply loop them by name or something, and change their name with javascript by assigning the right index.
A kick-off example with jQuery:
$(function() {
$('#myform').submit(function() {
$('[name^="myCollection[]"]').each(function(index) {
var oldV = this.name;
var newV = oldV.replace("myCollection[]", "myCollection[" + index + "]");
console.log("was: " + oldV + " - now is: " + newV);
this.name = newV;
});
return false;
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<form id="myform">
Open Javascript Console, then press submit, then inspect input elements
<br>
<input name="myCollection[].myProperty" />
<br>
<input name="myCollection[].myProperty" />
<br>
<input name="myCollection[].myProperty" />
<br>
<input name="myCollection[].myProperty" />
<br>
<input name="myCollection[].myProperty" />
<br>
<button>submit</button>
</form>

You need somehow to identify which object some property belongs to. Indexes are simplest way to do that, so you cannot just remove them.
There are many ways to achieve what you want. Look at Andrea's answer for one possible solution using javascript.
You can also pull object properties to simple lists and later set them to object.
E.g.
private List<String> myProperty;
can be referenced in JSP w/o indexes:
<input name="myProperty" value="first value" />
<input name="myProperty" value="second value" />
Of course you if you have many properties you need to somehow sync them in JSP in such way that order and size of the properties in list is consistent for every property.

Checking the names of elements from an array of objects selected by jquery

I'm a beginner in js and jquery library. I'd like to get an array of input fields with a particular name, and validate input. Each of my input fields have a name like NS[0], NS[1] etc. The total number of fields will have to be determined by the code, since the fields are generated by javascript.
I know that I can have jquery address the individual object like this:
$("input[name=NS\\[0\\]]").val() for <input type="text" name="NS[0]">.
However, how can I get an array of all these similiar elements, from NS[0] to NS[x] where x has to be determined based on how many fields have been generated? I already have other fields with different name patterns sharing the same css class, so using class is not an option. These boxes are in a particular div area, but in the same area are other input fields, so choosing all input boxes of the same area selects them as well.
In other words, how do I use jquery to check the name of each input field, after getting the entire array of input fields, to check each individual name?
Since I have input fields of various names in the area determined by the table id CNTR1, I would select them with $('#CNTR1 input'). I can also select individual fields by using $("input[name=]"). However, what I want to do, is to select everything under $('#CNTR1 input'), and then run a loop on their names, checking whether the names match a predetermined criteria. How can I do that?
The html code:
<table class="table" id="cnservers">
<thead>
<tr>
<th>Type</th>
<th>Preference</th>
<th>Value</th>
<th>Name</th>
</tr>
</thead>
<tr id="CNTR0">
<td>CNAME</td><td><input type="text" name="CN_PREF[0]" value=""></td><td>
<input type="text" name="CN_VAL[0]" value=""></td><td>
<input type="text" name="CN_NAME[0]" value="">
<a class="btn btn-danger" onclick="DelField(this.id);" id="CN_D0" >
<span class="btn-label">Delete
</span>
</a>
<a class="btn btn-primary" onclick="addField('cnservers','CN',10);" id="CN_A0" >
<span class="btn-label">Add
</span>
</td></tr>
</table>
[1]: http://i.stack.imgur.com/bm0Jq.jpg

I must be missing something. Is there a reason you can't use the http://api.jquery.com/attribute-starts-with-selector/?
$('#CNTR1').find('input[name^="NS"]')
Regarding,
However, what I want to do, is to select everything under $('#CNTR1 input'), and then run a loop on their names, checking whether the names match a predetermined criteria. How can I do that?
$("#CNTR1 input").each(function(index, elem) {
var $elem = $(elem),
name = $elem.attr('name');
var nameMatchesCondition = true; // replace with your condition
if (nameMatchesCondition) {
// do something!
}
});
EDIT 1:
Well, id is still an attribute of an html element. So you could do $('[id^="CNTR1"]') ... The value of the id attribute of an element doesn't contain the #. It's only part of the css/jquery selector. When using attribute style selectors, you don't need it. Though I can't comment on the performance of this.
Ideally, you want to attach a second class, say js-cntr to all elements that you created with an id starting with CNTR. Even though different name pattern elements may already have one class, that class is for styling. There is no stopping you from attaching custom classes purely for selection via js. This is an accepted thing to do and which is why the class name starts with js-, to denote that its purely for use via js for selection.

Try this
HTML
<table id="CNTR1">
<tr>
<td>CNAME</td>
<td><input type="text" name="CN_PREF[1]" id="CN_IN[1]"></td>
<td><input type="text" name="CN_VAL[1]"></td>
<td><input type="text" name="CN_NAME[1]"></td>
</tr>
</table>
JS
$(document).ready(function(){
$("#CNTR1 input").each(function() {
console.log($(this).attr("name"));
// Match With predetermined criteria
});
});

Use jQuery's .filter method, with a filter function:
filterCritera = /^CN_NAME\[/; // or whatever your criteria is
var inputs = $('#CNTR0 input');
// you could also cache this filter in a variable
inputs.filter(function(index){
return filterCritera.test(this.name);
}).css('background','red');
jsbin
The markup you posted does not the markup described in your question ( it does not contain NS[0]) but you can substitute it in the reguluar expression above.

How to create dynamic row of table using Struts 1.3 and javascript

I have a contact table, this table contains a first name, a last name, and multiple phone numbers. So my model is something like
Contact {
String firstName;
String lastName;
List phones;
}
Phone {
String category; //home, work, mobile, etc
String phoneNumber;
}
So it will have web page contains two input text for first name and last name, and an add phone button. When add button is clicked, it will generate two input text again for category and phone number, and an delete button to that row.
I have tried using indexed=true, it will generate an html like
<input type="text" name="phone[0].category" ... />
<input type="text" name="phone[0].phoneNumber" ... />
The problem is, i dont know how to write the javascript, because i dont know what is current index if user click add button, how about if user have clicked delete button and then add button, what index it will be? It is ok if i have missing index? Something like
<input type="text" name="phone[0].category" ... />
<input type="text" name="phone[0].phoneNumber" ... />
<input type="text" name="phone[3].category" ... />
<input type="text" name="phone[3].phoneNumber" ... />
Note: please consider for the edit scenario too.

The first thing here is to use well the indexed and logic:iterate tags to generate the code. If having doubts about this, check out this answer given by me, which explains in detail how to use indexed attributes in struts: indexed and logic:iterate
Then, you have to consider the scenario where an user wants to add or delete rows, and update indexes correctly so struts will be able to retrieve data as you submit the form. I encountered this problem once and what I did was:
on add: using javascript, find out what is the last line of the table and, by looking at the generated code of the page, generate a new table row with empty contents, the index inside the square brackets. Finally, add to table
EXAMPLE:
a table:
<table><tr><td name='whatever[0].something'>asdf</td></tr>
<tr><td name='whatever[1].something'>asdf</td></tr>
<tr><td name='whatever[2].something'>asdf</td></tr>
</table>
to add a row, create it in javascript like this:
var newRow = '<tr><td name='whatever[3].something'>asdf</td></tr>
and append it to the table.
on del:Using the same technique as above find out which line (or corresponding index) was deleted. Then, edit the indexes of the remaining rows so that it matches the order of elements for the subsequent rows.
EXAMPLE:
a table:
<table><tr><td name='whatever[0].something'>asdf0</td></tr>
<tr><td name='whatever[1].something'>asdf1</td></tr>
<tr><td name='whatever[2].something'>asdf2</td></tr>
</table>
let's say you delete asdf1 by removing it from the dom. then, the new table will look like this:
<table><tr><td name='whatever[0].something'>asdf0</td></tr>
<tr><td name='whatever[2].something'>asdf2</td></tr>
</table>
now we have to update indexes so it matches the right order, by changing the name of the second td to have an index of 1, that way, the table is back to a struts indexed format:
<table><tr><td name='whatever[0].something'>asdf0</td></tr>
<tr><td name='whatever[1].something'>asdf2</td></tr>
</table>
I hope it's clear enough. I obviously can't write all the js functions, since they require some work, but with this information you can make it on your own.

Accessing an array of HTML input text boxes using jQuery or plain Javascript

I'm looking to create a form which contains a dynamic number of input text boxes. I would like each text box to form part of an array (this would in theory make it easier for me to loop through them, especially as I won't know the number of text fields that will eventually exist). The HTML code would like something like:
<p>Field 1: <input type="text" name="field[1]" id="field[1]"></p>
<p>Field 2: <input type="text" name="field[2]" id="field[2]"></p>
<p>Field 3: <input type="text" name="field[3]" id="field[3]"></p>
<p>Field 4: <input type="text" name="field[4]" id="field[4]"></p>
<p>Field 5: <input type="text" name="field[5]" id="field[5]"></p>
This data would then be sent to a PHP script and would be represented as an array - or at least, that's the theory.
So my first question is, is this achievable using HTML? Are forms designed to work that way?
If the answer to that is "yes", how would I then go about accessing each of those using jQuery or failing that, plain old JavaScript?
I've attempted to achieve this using the following jQuery code:
someval = $('#field[1]').val();
and
someval = $('#field')[1].val();
and the following JavaScript:
someval = document.getElementById('related_link_url')[1].value;
But I've not had any luck.
Thanks in advance.
Edit:
I should note that from a Javascript point of view, I've had it working where the ID of each element is something like field_1, field_2 etc. However, I feel that if I can achieve it by placing each text box into an array, it would make for tidier and easier to manage code.

Give each element a class and access the group using jQuery:
<p>Field 1: <input type="text" name="field[1]" class="fields"></p>
<p>Field 2: <input type="text" name="field[2]" class="fields"></p>
<!-- etc... -->
jQuery:
$("input.fields").each(function (index)
{
// Your code here
});
This will run the anonymous function on each input element with a classname of "fields", with the this keyword pointing to the current element. See http://api.jquery.com/each/ for more info.

First of all, id attribute cannot contains [ or ] character.
There is lots of ways to get jQuery/plain JavaScript references to these elements. You can use descendant selector:
<fieldset id="list-of-fields">
<!-- your inputs here -->
</fieldset>
$("#list-of-fields input");
document.getElementById("list....").getElementsByTagName("input");
You can also use attribute selector:
$("input[name^=field]");
I'm not sure whether that's the only way but I think in plain JavaScript you'll have to fetch all input elements (document.getElementsByTagName) and then loop through array of these elements and check each element (whether it has name attribute which value starts with field).