I'm stuck trying to retrieve the selected value from a 'select' element via javascript. I can't even get the element from the DOM with either jQuery or document.getElementById().
Here is my code:
function getDropdown(headerText, options, id) {
var container = document.createElement('div');
container.setAttribute('class', 'nfvo-drop-down-container');
var dd = document.createElement('select');
$(dd).attr('id', id);
for(var val in options) {
$('<option />', {value: val, text: options[val]}).appendTo(dd);
}
if(headerText) {
var span = document.createElement('span');
span.setAttribute('class', 'panel-header');
span.appendChild(document.createTextNode(headerText));
container.appendChild(span);
}
container.appendChild(dd);
return container;
}
var dd = getDropDown('My dropdown', [1,2,3,4], 'ddID);
var e = document.getElementById('ddID');
var e2 = $('#ddID');
var e3 = $('#ddID').val();
var e4 = $('#ddID').text();
If I were to console.log these values I would get these results:
console.log(e) -> 'null'
console.log(e2) -> <Got the element>
console.log(e3) -> 'undefined'
console.log(e4) -> <Nothing, just a blank>
Any ides on what might cause this problem?
This block of code is within a '.then' function call e.g:
$.when(...).then(function(...)
<Here is the code>
);
EDIT: There was a typo in the post which have now been fixed. This is not the source of my problem.
I should also mention that I add this div to a ContentPane via the Dojo toolkit and I can see dropdown in the DOM via the inspection tool in chrome.
You won't get select box object by using document.getElementById('ddID')
since you have not added your object to any object in the document.
You will get select box object from the dd object by using dd.childNodes[1]
getDropDown creates an element with that id, puts it in a div, and then returns the div.
It never adds any of those elements to any element in the document.
Thus, when you search the document for an element with the matching id, it isn't there.
Related
I always used jQuery before, but I want to switch the following to native javascript for better performance of the website.
var first = $('ul li:first');
var first = $('ul li:last');
$(last).before(first);
$(first).after(last);
From: http://clubmate.fi/append-and-prepend-elements-with-pure-javascript/
Before (prepend):
var el = document.getElementById('thingy'),
elChild = document.createElement('div');
elChild.innerHTML = 'Content';
// Prepend it
el.insertBefore(elChild, el.firstChild);
After (append):
// Grab an element
var el = document.getElementById('thingy'),
// Make a new div
elChild = document.createElement('div');
// Give the new div some content
elChild.innerHTML = 'Content';
// Jug it into the parent element
el.appendChild(elChild);
To get the first and last li:
var lis = document.getElementById("id-of-ul").getElementsByTagName("li"),
first = lis[0],
last = lis[lis.length -1];
if your ul doesn't have an id, you can always use getElementsByTagName("ul") and figure out its index but I would advise adding an id
I guess you are looking for:
Element.insertAdjacentHTML(position, text);
Where position is:
'beforebegin'.
Before the element itself.
'afterbegin'.
Just inside the element, before its first child.
'beforeend'.
Just inside the element, after its last child.
'afterend'.
After the element itself.
And text is a HTML string.
Doc # MDN
You can use insertBefore():
var node = document.getElementById('id');
node.parentNode.insertBefore('something', node);
Documentation: insertBefore()
There is no insertAfter method. It can be emulated by combining the insertBefore method with nextSibling():
node.parentNode.insertBefore('something', node.nextSibling);
I'm trying to swap select option values with jQuery when a links clicked, at the moment its just resetting the select when the links clicked, not sure what's going wrong?:
jQuery:
$(function () {
$("#swapCurrency").click(function (e) {
var selectOne = $("#currency-from").html();
var selectTwo = $("#currency-to").html();
$("#currency-from").html(selectTwo);
$("#currency-to").html(selectOne);
return false;
});
});
JS Fiddle here: http://jsfiddle.net/tchh2/
I wrote it in a step-by-step way so it is easier to understand:
$("#swapCurrency").click(function (e) {
//get the DOM elements for the selects, store them into variables
var selectOne = $("#currency-from");
var selectTwo = $("#currency-to");
//get all the direct children of the selects (option or optgroup elements)
//and remove them from the DOM but keep events and data (detach)
//and store them into variables
//after this, both selects will be empty
var childrenOne = selectOne.children().detach();
var childrenTwo = selectTwo.children().detach();
//put the children into their new home
childrenOne.appendTo(selectTwo);
childrenTwo.appendTo(selectOne);
return false;
});
jsFiddle Demo
Your approach works with transforming DOM elements to HTML and back. The problem is you lose important information this way, like which element was selected (it is stored in a DOM property, not an HTML attribute, it just gives the starting point).
children()
detach()
appendTo()
That happens because you remove all elements from both <select> fields and put them as new again. To make it working as expected you'd better move the actual elements as follows:
$("#swapCurrency").click(function(e) {
var options = $("#currency-from > option").detach();
$("#currency-to > option").appendTo("#currency-from");
$("#currency-to").append(options);
return false;
});
DEMO: http://jsfiddle.net/tchh2/2/
You are replacing the whole HTML (every option) within the <select>. As long as each select has the same amount of options and they correspond to each other, you can use the selected index property to swap them:
$("#swapCurrency").click(function (e) {
var selOne = document.getElementById('currency-from'),
selTwo = document.getElementById('currency-to');
var selectOne = selOne.selectedIndex;
var selectTwo = selTwo.selectedIndex;
selOne.selectedIndex = selectTwo;
selTwo.selectedIndex = selectOne;
return false;
});
JSFiddle
Is it possible for this jQuery code to run as a standalone javascript? This is the only javascript I'd like to use in my project so I'd prefer not to load the entire jquery library just for this 1k script.
//chris coyier's little dropdown select-->
$(document).ready(function() {
//build dropdown
$("<select />").appendTo("nav.primary");
// Create default option "Go to..."
$("<option />", {
"selected": "selected",
"value" : "",
"text" : "Go to..."
}).appendTo("nav select");
// Populate dropdowns with the first menu items
$("div#brdmenu ul li a").each(function() {
var el = $(this);
$("<option />", {
"value" : el.attr("href"),
"text" : el.text()
}).appendTo("nav.primary select");
});
//make responsive dropdown menu actually work
$("nav.primary select").change(function() {
window.location = $(this).find("option:selected").val();
});
});
I've tried to find previous answers but most questions are for converting to jquery and not vice-versa :)
It is obviously possible to do those things in straight javascript, but there is no way (that I am aware of) to automatically do that conversion. You will have to go through line by line and do the conversion yourself.
Here is something similar to market's answer. I'm assuming you want to get all the links in UL elements inside the brdmenu element. If you only want the first link on the LI elements, just adjust the loop that gets them.
Also, this is not a good idea. Using select elements for links went out of fashion a long time ago, users much prefer real links. Also, when navigating the options using cursor keys in IE, a change event is dispatched every time a different option is selected so users will only get to select the next option before being whisked away to that location. Much better to add a "Go" button that they press after selecting a location.
The main change is to use an ID to get the nav.primary element, which I assume is a single element that you should be getting by ID already.
function doStuff() {
function getText(el) {
return el.textContent || el.innerText;
}
var div, link, links, uls;
// Use an ID to get the nav.primary element
var navPrimary = document.getElementById('navPrimary');
// Create select element and add listener
var sel = document.createElement('select');
sel.onchange = function() {
if (this.selectedIndex > 0) { // -1 for none selected, 0 is default
window.location = this.value;
}
};
// Create default option and append to select
sel.options[0] = new Option('Go to...','');
sel.options[0].setAttribute('selected','');
// Create options for the links inside #brdmenu
div = document.getElementById('brdmenu');
uls = div.getElementsByTagName('ul');
for (var i=0, iLen=uls.length; i<iLen; i++) {
links = uls[i].getElementsByTagName('a');
for (var j=0, jLen=links.length; j<jLen; j++) {
link = links[j];
sel.appendChild(new Option(getText(link), link.href));
}
}
// Add select to page if found navPrimary element
if (navPrimary) {
navPrimary.appendChild(sel);
}
}
window.onload = doStuff;
It's only 28 lines of actual code, which is only 10 more than the original, doesn't require any supporting library and should work in any browser in use (and most that aren't).
Have a go with this.
The one thing I'm leaving out is $(document).ready, but there are a number of solutions for that available on stackoverflow. It's a surprisingly large amount of code!
But the other functionality:
// build the dropdown
var selectElement = document.createElement('select');
var primary = document.getElementsByClassName('primary')[0];
// create a default option and append it.
var opt = document.createElement('option');
var defaultOpt = opt.cloneNode(false);
defaultOpt.selected = true;
defaultOpt.value = "";
defaultOpt.text = "Go to...";
selectElement.appendChild(defaultOpt);
// populate the dropdown
var brdmenuUl = document.getElementById('brdmenu').getElementsByTagName('ul')[0];
var listItems = brdmenuUl.getElementsByTagName('li');
for(var i=0; i<listItems.length; i++){
var li = listItems[i];
var a = li.getElementsByTagName('a')[0];
var newOpt = opt.cloneNode(false);
newOpt.value = a.href;
newOpt.text = a.innerHTML;
selectElement.appendChild(newOpt);
}
// now listen for changes
if(selectElement.addEventListener){
selectElement.addEventListener('change', selectJump, false);
}
else if(selectElement.attachEvent){
selectElement.attachEvent('change', selectJump);
}
function selectJump(evt){
window.location = evt.value;
}
primary.appendChild(selectElement);
some notes!
We're not looking specifically for nav.primary, we're just finding the first occurrence of something with class .primary. For best performance, you should add an ID to that element and use getElementById instead.
Similarly with the lists in #brdmenu, we look for the first UL, and the first A inside each LI. This isn't exactly what the jQuery does, if you are going to need to iterate more than one UL inside #brdmenu you can use another for loop.
I think that should all work though, there's a fiddle here
I have a very simple HTML page. After everything is loaded, the user can interact with it perfectly. Now, at some point, the user clicks on an element. An ajax call is made and new data is being requested. I now want to remove the previous element the user clicked on with the element(s) the user has requested (on the same page) - practically remove the old element from the DOM and add the new one. Well, I did this as well, but I am unable to add a function to the newly created element. This is my function:
setCountry = function(value){
document.getElementById('country').innerHTML = value;
}
and I'm trying to add it like this to my element
a_tag.setAttribute("href", "javascript:setCountry(countries[i]);");
The function is being called and writes "undefined" to the innerHTML element. I set the attribute using a for loop and just above the for loop I alert an element from the array to be sure it's correct, and it prints out the correct value.
I assume the problem happens because the function is being created on the first load of the DOM, but I'm not sure. Can anyone shed some light on what is really happening here and what I should do to correct it? I want to be able to add more functions so not looking for a work around writing an innerHTML tag, I just want to understand what I'm doing wrong.
Thank you.
Edited with more code
//declare an array to hold all countries form the db
var countries = new Array();
function getCountries(region) {
document.getElementById('scroller').innerHTML = '';
//send the data to the server and retreive a list of all the countries based on the current region
$.ajax({
type: "POST",
url: "scripts/get_countries.php",
data: {
region: region
},
success: saveDataToArray,
async: false,
dataType: 'json'
});
//save the data to an array
function saveDataToArray(data){
var i = 0;
while (data[i]){
countries[i] = data[i];
i++;
}
}
scroller = document.getElementById('scroller');
//create a ul element
var holder = document.createElement("ul");
//here create a back button which will recreate the whole list of regions
var total = countries.length;
for(i=0;i<total;i++){
//create the first field in the list
var bullet_item = document.createElement("li");
//create an a tag for the element
var a_tag = document.createElement("a");
//set the redirect of the tag
a_tag.setAttribute("href", "javascript:setCountry(this);");
//create some text for the a_tag
var bullet_text = document.createTextNode(countries[i]);
//apend the text to the correct element
a_tag.appendChild(bullet_text);
//apend the a_tag to the li element
bullet_item.appendChild(a_tag);
//apend the item to the list
holder.appendChild(bullet_item);
}
//apend the holder to the scroller
scroller.appendChild(holder);
}
function setRegion(region){
document.getElementById('region').innerHTML = region;
}
setCountry = function(value){
document.getElementById('country').innerHTML = value;
}
There is no need for quoting the code in a string. Instead of this:
a_tag.setAttribute("href", "javascript:...")
Try to form a closure:
a_tag.onclick = function () { ... }
Note that by default <A> elements without HREF do not look normal, but you can fix that with CSS.
Problem solved
Everything was good apart from the way I was declaring the href parameter
a_tag.setAttribute("href", "javascript:setCountry("+'"'+countries[i]+'"'+")");
it's all the usual, a game of single quotes and double quotes.
Thanks everyone for pitching in ideas. Much appreciated as usual
Adrian
I got some help earlier regarding selectors, but I'm stuck with the following.
Lets say you have a plugin like this
$('#box').customplugin();
how can I get the #box as a string in the plugin?
Not sure if that's the correct way of doing it, and any other solution would be great as well.
Considering #box is a select dropdown,
The problem I'm having is if I do the regular javascript
$('#box').val(x);
The correct option value gets selected,
but if i try the same inside a plugin
.....
this.each(function() {
var $this = $(this);
$this.val(x);
the last code doesn't really do anything.
I notice I'm having trouble targeting #box inside the plugin because it's a object and not a string...
Any help would be appreciated.
Thanks!
Edit:: Putting in the code I'm working in for better understanding
(function($){
$.fn.customSelect = function(options) {
var defaults = {
myClass : 'mySelect'
};
var settings = $.extend({}, defaults, options);
this.each(function() {
// Var
var $this = $(this);
var thisOpts = $('option',$this);
var thisSelected = $this[0].selectedIndex;
var options_clone = '';
$this.hide();
options_clone += '<li rel=""><span>'+thisOpts[thisSelected].text+'</span><ul>'
for (var index in thisOpts) {
//Check to see if option has any text, and that the value is not undefined
if(thisOpts[index].text && thisOpts[index].value != undefined) {
options_clone += '<li rel="' + thisOpts[index].value + '"><span>' + thisOpts[index].text + '</span></li>'
}
}
options_clone += '</ul></li>';
var mySelect = $('<ul class="' + settings.myClass + '">').html(options_clone); //Insert Clone Options into Container UL
$this.after(mySelect); //Insert Clone after Original
var selectWidth = $this.next('ul').find('ul').outerWidth(); //Get width of dropdown before hiding
$this.next('ul').find('ul').hide(); //Hide dropdown portion
$this.next('ul').css('width',selectWidth);
//on click, show dropdown
$this.next('ul').find('span').first().click(function(){
$this.next('ul').find('ul').toggle();
});
//on click, change top value, select hidden form, close dropdown
$this.next('ul').find('ul span').click(function(){
$(this).closest('ul').children().removeClass('selected');
$(this).parent().addClass("selected");
selection = $(this).parent().attr('rel');
selectedText = $(this).text();
$(this).closest('ul').prev().html(selectedText);
$this.val(selection); //This is what i can't get to work
$(this).closest('ul').hide();
});
});
// returns the jQuery object to allow for chainability.
return this;
}
Just a heads-up: .selector() is deprecated in jQuery 1.7 and removed in jQuery 1.9: api.jquery.com/selector.
– Simon Steinberger
Use the .selector property on a jQuery collection.
Note: This API has been removed in jQuery 3.0. The property was never a reliable indicator of the selector that could be used to obtain the set of elements currently contained in the jQuery set where it was a property, since subsequent traversal methods may have changed the set. Plugins that need to use a selector string within their plugin can require it as a parameter of the method. For example, a "foo" plugin could be written as $.fn.foo = function( selector, options ) { /* plugin code goes here */ };, and the person using the plugin would write $( "div.bar" ).foo( "div.bar", {dog: "bark"} ); with the "div.bar" selector repeated as the first argument of .foo().
var x = $( "#box" );
alert( x.selector ); // #box
In your plugin:
$.fn.somePlugin = function() {
alert( this.selector ); // alerts current selector (#box )
var $this = $( this );
// will be undefined since it's a new jQuery collection
// that has not been queried from the DOM.
// In other words, the new jQuery object does not copy .selector
alert( $this.selector );
}
However this following probably solves your real question?
$.fn.customPlugin = function() {
// .val() already performs an .each internally, most jQuery methods do.
// replace x with real value.
this.val(x);
}
$("#box").customPlugin();
This page talks about getting the selector:
http://api.jquery.com/selector/
That's how I get selector strings inside my plugins in 2017:
(function($, window, document, undefined) {
$.fn._init = $.fn.init
$.fn.init = function( selector, context, root ) {
return (typeof selector === 'string') ? new $.fn._init(selector, context, root).data('selector', selector) : new $.fn._init( selector, context, root );
};
$.fn.getSelector = function() {
return $(this).data('selector');
};
$.fn.coolPlugin = function() {
var selector = $(this).getSelector();
if(selector) console.log(selector); // outputs p #boldText
}
})(jQuery, window, document);
// calling plugin
$(document).ready(function() {
$("p #boldText").coolPlugin();
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p>some <b id="boldText">bold text</b></p>
The idea is to conditionally wrap jQuery's init() function based on whether a selector string is provided or not. If it is provided, use jQuery's data() method to associate the selector string with the original init() which is called in the end. Small getSelector() plugin just takes previously stored value. It can be called later inside your plugin. It should work well with all jQuery versions.
Because of the deprecation and removal of jQuery's .selector, I have experimented with javascript's DOM Nodes and came up with a 2017 and beyond solution until a better way comes along...
//** Get selector **//
// Set empty variables to work with
var attributes = {}, // Empty object
$selector = ""; // Empty selector
// If exists...
if(this.length) {
// Get each node attribute of the selector (class or id)
$.each(this[0].attributes, function(index, attr) {
// Set the attributes in the empty object
// In the form of name:value
attributes[attr.name] = attr.value;
});
}
// If both class and id exists in object
if (attributes.class && attributes.id){
// Set the selector to the id value to avoid issues with multiple classes
$selector = "#" + attributes.id
}
// If class exists in object
else if (attributes.class){
// Set the selector to the class value
$selector = "." + attributes.class
}
// If id exists in object
else if (attributes.id){
// Set the selector to the id value
$selector = "#" + attributes.id
}
// Output
// console.log($selector);
// e.g: .example #example
So now we can use this for any purpose. You can use it as a jQuery selector... eg. $($selector)
EDIT: My original answer would only get the attribute that appears first on the element. So if we wanted to get the id that was placed after the class on the element, it wouldn't work.
My new solution uses an object to store the attribute information, therefore we can check if both or just one exists and set the required selector accordingly. With thanks to ManRo's solution for the inspiration.