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Selecting a drop-down box option does not affect page

I'm trying to make an extension that selects facilitates filling out info on checkout page of a website (you'll probably have to add to cart before you can go to the checkout page). Currently I'm just setting the "selected" value of a certain option tag to be true, but it seems not to affect the page as intended. I'm talking about the Country and State selection on the checkout page (I want it to be Canada and BC). Would prefer vanilla Javascript
Here's my code:
var checkoutSelects = document.querySelectorAll("select:not([type=hidden])");
for(var i = 0; i < checkoutSelects.length; i++) {
if(checkoutSelects[i].getAttribute("id").toLowerCase().includes('country')) {
var countryOptions = checkoutSelects[i].querySelectorAll('option');
for(var a = 0; a < countryOptions.length; a++) {
if(countryOptions[a].value.toLowerCase().includes("canada")) {
countryOptions[a].selected = true;
}
}
}
}

Can you try countryOptions.selectedIndex = a;
instead of
countryOptions[a].selected = true;

How to improve jQuery performance with appending icons?

I am building a spreadsheet editor with jQuery and I am encountering performance issues with big tables.
The table holds many data sets and when clicked on one, icons are added to the first cell of the other sets. The code looks like this:
$('.click_icon').remove();
for (var i = 0; i < datasets.length; i++) {
var first_cell = $('td.content[dataset="' + datasets[i].id + '"]').filter(':first');
if (in_group(datasets[i].id)) {
first_cell.append('<i class="icon-remove click_icon remove_group" style="float:right"></i>');
} else {
first_cell.append('<i class="icon-magnet click_icon add_group" style="float:right"></i>');
}
with 500+ datasets this takes about 5 seconds. in_group() is just a small function which checks if the set is in a group with the selected data set.
I was wondering if creating the icons prior to the click and using show() hide() would be faster? Any other ideas?
I am using Chromium on Ubuntu. (Version 28.0.1500.52 Ubuntu 12.04)

Build the table in memory and only change the DOM once :
$('.click_icon').remove();
var table = $('table');
var clone = table.clone(true);
for (var i = 0; i < datasets.length; i++) {
var _class = in_group(datasets[i].id) ?
'icon-remove click_icon remove_group' :
'icon-magnet click_icon add_group',
elem = $('<i />', {'class': _class, style:'float:right'});
$('td.content[dataset="' + datasets[i].id + '"]', clone).filter(':first')
.append(elem);
}
table.replaceWith(clone);
This is a general example, you may have to adjust this to make it work properly with your markup.
I'd normally use plain JS for performance, and documentFragments, but I think jQuery uses fragments internally when doing it this way.

In my experience, appending element by string is worst for performance than creating element by DOM.
So try anything like this:
if (in_group(datasets[i].id)) {
var i = document.createElement('i');
i.className = 'icon-remove click_icon remove_group';
i.style.float = 'right';
first_cell.appendChild(i);
}

If you expect the users to click, I think creating the icons prior to the click is a good idea.
Instead of show/hide which toggles the display property, you could use the visibility property. When the visibility changes from hidden to visible, the browser doesn't need to recalculate the layout.

How to set input field maxlength from label

I'm trying to figure out a way to change the maxlength of ajax called input fields by pulling the value to set out of the field's label and updating the default value. The field labels all follow the same format - id, class, type and maxlength. The new maxlength value to set is always present in the id ...max_X_characters...
`<input id="ecwid-productoption-16958710-Line_5_:0028max_4_characters:0029" class="gwt-
TextBox ecwid-productBrowser-details-optionTextField ecwid-productoption-
Line_5_:0028max_4_characters:0029" type="text" maxlength="200"></input>`
So in this example I need to set the maxlength to 4.
The other problem is that there are multiple input fields, often with different maxlength values. See here for an example.
I was thinking of setting a script to pull out the value once the fields have loaded, but I don't mind admitting it, this one's over my head - hopefully one of you bright guys n gals can figure it out!
Update: Thanks for the suggestions, I've tried both, in various combinations, but can't get them to work.
Here's the code suggested by Ecwid's tech team that sets all input fields on the page to one maxlength (6 in this case)
`Ecwid.OnPageLoaded.add(function(page){if (page.type == "PRODUCT") {
$("input.ecwid-productBrowser-details-optionTextField").attr('maxlength','6');
};
})`
However, as I stated there are input fields with different maxlengths for some products.
I've tried replacing the '6' above with a function, based on your suggestions, to get the maxlength from the input id, but can't get it to work.
Any more ideas?
Thanks
Update:
Cracked it (nearly), here's the working code
`Ecwid.OnPageLoaded.add(function(page){
var regex = new RegExp("max_(\\d+)_characters");
var inputs = document.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
var inp = inputs[i];
if (regex.test(inp.id)) {
var newLimit = inp.id.match(regex)[1];
inp.maxLength = newLimit;
}
}
});`
Thanks so much for your help, it works like a dream on the product page but there is another area where it doesn't. A customer can edit the input text via a pop-up, from the shopping basket.
The fields have similar code:
`<input id="ecwid-productoption-16958710-Line_5_:0028max_4_characters:0029"
class="gwt-TextBox ecwid-productBrowser-details-optionTextField ecwid-productoption-
Line_5_:0028max_4_characters:0029" type="text" maxlength="200"></input>`
Suggestions very welcome
Chris
UPDATE:
Many, many, many thanks to ExpertSystem (you genius you!) - I think we've got it. (tested on IE10, firefox 21, chrome 27).
The code below is for people using Yola and Ecwid together, but I guess the original code may work for people using other sitebuilders. It limits the number of characters a user can enter into input fields, in Ecwid, by checking for a number in the input field's title (in this case the value between 'max' and 'characters') and replacing that as the field's maxLength value. It limits fields in the product browser, in the html widgets and in the cart pop-up.
Here it is:
Go to Yola's Custom Site Tracking Code section. In the 'Footer Code' column (actually placed at the bottom of the 'body'), place this code:
<script>
Ecwid.OnPageLoaded.add(function(page){
var regex = new RegExp("max_(\\d+)_characters");
var inputs = document.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
var inp = inputs[i];
if (regex.test(inp.id)) {
var newLimit = inp.id.match(regex)[1];
inp.maxLength = newLimit;
}
}
});
</script>
<script>
var regex = new RegExp("max_(\\d+)_characters");
function fixMaxLength(container) {
var inputs = container.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
var inp = inputs[i];
if (regex.test(inp.id)) {
var newLimit = inp.id.match(regex)[1];
inp.maxLength = newLimit;
}
}
};
</script>
and this into the 'Header Code' column:
<script>
document.addEventListener("DOMNodeInserted", function() {
var popups = document.getElementsByClassName("popupContent");
for (var i = 0; i < popups.length; i++) {
fixMaxLength(popups[i]);
}
});
</script>
That's it! You're good to go.

It is not exactly clear what is meant by "ajax called input fields", but supposing that the input fields are created and added to DOM inside a success callback for some AJAX call, you can place the following piece of code in your pages <head>:
var regex = new RegExp("max_(\\d+)_characters");
function fixMaxLength(container) {
var inputs = container.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
var inp = inputs[i];
if (regex.test(inp.id)) {
var newLimit = inp.id.match(regex)[1];
inp.maxLength = newLimit;
}
}
}
And then, at the end of the AJAX call's "onSuccess" callback, append this:
fixMaxLength(document);
UPDATE:
Based on your comments below, if you need to apply fixMaxLength() to div's of class "popupContent", which get dynamically added to your DOM, an easy way (not the most efficient though) would be adding a listener for DOM modification events (e.g. somewhere in <head>):
document.addEventListener("DOMNodeInserted", function() {
var popups = document.getElementsByClassName("popupContent");
for (var i = 0; i < popups.length; i++) {
fixMaxLength(popups[i]);
}
});
(NOTE: I have only tested it on latest versions of Chrome and Firefox, so I am not really sure for which other/older browsers this does work.)
(NOTE2: GGGS, has tested it (and found it working) on IE10 as well.)

How about a regular expression on your id attribute? Such as the following:
jQuery('input').each(function() {
var idVal = jQuery(this).attr('id');
var regex = /max_(\d+)_characters/g;
var result = regex.exec(idVal);
var length = result[1];
});
This is a loop over all the inputs. Once this is run, the length variable will have the proper length each go through, for your next step.

JavaScript: get custom button's text value

I have a button that is defined as follows :
<button type="button" id="ext-gen26" class=" x-btn-text">button text here</button>
And I'm trying to grab it based on the text value. Hhowever, none of its attributes contain the text value. It's generated in a pretty custom way by the look of it.
Does anyone know of a way to find this value programmatically, besides just going through the HTML text? Other than attributes?
Forgot one other thing, the id for this button changes regularly and using jQuery to grab it results in breaking the page for some reason. If you need any background on why I need this, let me know.
This is the JavaScript I am trying to grab it with:
var all = document.getElementsByTagName('*');
for (var i=0, max=all.length; i < max; i++)
{
var elem = all[i];
if(elem.getAttribute("id") == 'ext-gen26'){
if(elem.attributes != null){
for (var x = 0; x < elem.attributes.length; x++) {
var attrib = elem.attributes[x];
alert(attrib.name + " = " + attrib.value);
}
}
}
};
It only comes back with the three attributes that are defined in the code.
innerHTML, text, and textContent - all come back as null.

You can do that through the textContent/innerText properties (browser-dependant). Here's an example that will work no matter which property the browser uses:
var elem = document.getElementById('ext-gen26');
var txt = elem.textContent || elem.innerText;
alert(txt);
http://jsfiddle.net/ThiefMaster/EcMRT/
You could also do it using jQuery:
alert($('#ext-gen26').text());

If you're trying to locate the button entirely by its text content, I'd grab a list of all buttons and loop through them to find this one:
function findButtonbyTextContent(text) {
var buttons = document.querySelectorAll('button');
for (var i=0, l=buttons.length; i<l; i++) {
if (buttons[i].firstChild.nodeValue == text)
return buttons[i];
}
}
Of course, if the content of this button changes even a little your code will need to be updated.

One liner for finding a button based on it's text.
const findButtonByText = text =>
[...document.querySelectorAll('button')]
.find(btn => btn.textContent.includes(text))

javascript dropdown to change all dropdown in table

I have a requirement of changing all dropdown values in all the rows in a tale based on master dropdown. say someone selects "value 2" in dropdown1, dropdown2 values in all the rows in the table should show "value2".
function change(){
var cid = document.frm.locdropdown.selectedIndex;
document.frm.locdropdown2.selectedIndex = cid;
}
is the java script I use to change it but this changes only first row.
please help..

From your example code it looks like you've given the same ID to all your locdropdown2 elements? Maybe you should post an example of your table HTML. It's normal practice to give unique IDs to elements, so you may want to test the NAME attribute instead, but anyway something like the following should work:
function change() {
var cid = document.frm.locdropdown.selectedIndex;
var inputs = document.getElementsByTagName("input");
for (var i=0, l = inputs.length; i < l; i++) {
if (inputs[i].id == "locdropdown2")
inputs[i].selectedIndex = cid;
}
}
Another option is to loop through each row in the table. The following example assumes your locdropdown2 inputs are the only thing in the third column, but you can adapt to suit your actual layout:
function change() {
var cid = document.frm.locdropdown.selectedIndex;
var tableRows = document.getElementById("yourTableId").tBodies[0].rows;
for (var i=0, l=tableRows.length; i < l; i++) {
tableRows[i].cells[2].firstChild.selectedIndex = cid;
}
}
Note: I haven't actually tested any of that code, but it should be more than enough to get you started and you can tweak as needed. (You can use Google to learn about tBodies, rows, cells, firstChild, etc.)