The example I see posted all of the time seems like it's suboptimal, because it involves concatenating strings, which seems so not jQuery. It usually looks like this:
$.getJSON("/Admin/GetFolderList/", function(result) {
for (var i = 0; i < result.length; i++) {
options += '<option value="' + result[i].ImageFolderID + '">' + result[i].Name + '</option>';
}
});
Is there a better way?
Andreas Grech was pretty close... it's actually this (note the reference to this instead of the item in the loop):
var $dropdown = $("#dropdown");
$.each(result, function() {
$dropdown.append($("<option />").val(this.ImageFolderID).text(this.Name));
});
$.getJSON("/Admin/GetFolderList/", function(result) {
var options = $("#options");
//don't forget error handling!
$.each(result, function(item) {
options.append($("<option />").val(item.ImageFolderID).text(item.Name));
});
});
What I'm doing above is creating a new <option> element and adding it to the options list (assuming options is the ID of a drop down element.
PS My javascript is a bit rusty so the syntax may not be perfect
Sure - make options an array of strings and use .join('') rather than += every time through the loop. Slight performance bump when dealing with large numbers of options...
var options = [];
$.getJSON("/Admin/GetFolderList/", function(result) {
for (var i = 0; i < result.length; i++) {
options.push('<option value="',
result[i].ImageFolderID, '">',
result[i].Name, '</option>');
}
$("#theSelect").html(options.join(''));
});
Yes. I'm still working with strings the whole time. Believe it or not, that's the fastest way to build a DOM fragment... Now, if you have only a few options, it won't really matter - use the technique Dreas demonstrates if you like the style. But bear in mind, you're invoking the browser's internal HTML parser i*2 times, rather than just once, and modifying the DOM each time through the loop... with a sufficient number of options. you'll end up paying for it, especially on older browsers.
Note: As Justice points out, this will fall apart if ImageFolderID and Name are not encoded properly...
Or maybe:
var options = $("#options");
$.each(data, function() {
options.append(new Option(this.text, this.value));
});
The fastest way is this:
$.getJSON("/Admin/GetFolderList/", function(result) {
var optionsValues = '<select>';
$.each(result, function(item) {
optionsValues += '<option value="' + item.ImageFolderID + '">' + item.Name + '</option>';
});
optionsValues += '</select>';
var options = $('#options');
options.replaceWith(optionsValues);
});
According to this link is the fastest way because you wrap everything in a single element when doing any kind of DOM insertion.
I found this to be working from jquery site
$.getJSON( "/Admin/GetFolderList/", function( data ) {
var options = $("#dropdownID");
$.each( data, function(key, val) {
options.append(new Option(key, val));
});
});
I've read that using document fragments is performant because it avoids page reflow upon each insertion of DOM element, it's also well supported by all browsers (even IE 6).
var fragment = document.createDocumentFragment();
$.each(result, function() {
fragment.appendChild($("<option />").val(this.ImageFolderID).text(this.Name)[0]);
});
$("#options").append(fragment);I first read about this in CodeSchool's JavaScript Best Practices course.
Here's a comparison of different approaches, thanks go to the author.
Other approach with ES6
fetch('https://restcountries.eu/rest/v1/all')
.then((response) => {
return response.json()
})
.then((countries) => {
var options = document.getElementById('someSelect');
countries.forEach((country) => {
options.appendChild(new Option(country.name, country.name));
});
})
I hope it helps. I usually use functions instead write all code everytime.
$("#action_selector").change(function () {
ajaxObj = $.ajax({
url: 'YourURL',
type: 'POST', // You can use GET
data: 'parameter1=value1',
dataType: "json",
context: this,
success: function (data) {
json: data
},
error: function (request) {
$(".return-json").html("Some error!");
}
});
json_obj = $.parseJSON(ajaxObj.responseText);
var options = $("#selector");
options.empty();
options.append(new Option("-- Select --", 0));
$.each(ajx_obj, function () {
options.append(new Option(this.text, this.value));
});
});
});
I use the selectboxes jquery plugin. It turns your example into:
$('#idofselect').ajaxAddOption('/Admin/GetFolderList/', {}, false);
$.get(str, function(data){
var sary=data.split('|');
document.getElementById("select1").options.length = 0;
document.getElementById("select1").options[0] = new Option('Select a State');
for(i=0;i<sary.length-1;i++){
document.getElementById("select1").options[i+1] = new Option(sary[i]);
document.getElementById("select1").options[i+1].value = sary[i];
}
});
function LoadCategories() {
var data = [];
var url = '@Url.Action("GetCategories", "InternalTables")';
$.getJSON(url, null, function (data) {
data = $.map(data, function (item, a) {
return "<option value=" + item.Value + ">" + item.Description + "</option>";
});
$("#ddlCategory").html('<option value="0">Select</option>');
$("#ddlCategory").append(data.join(""));
});
}
function generateYears() {
$.ajax({
type: "GET",
url: "getYears.do",
data: "",
dataType: "json",
contentType: "application/json",
success: function(msg) {
populateYearsToSelectBox(msg);
}
});
}
function populateYearsToSelectBox(msg) {
var options = $("#selectYear");
$.each(msg.dataCollecton, function(val, text) {
options.append(
$('<option></option>').val(text).html(text)
);
});
}
here is an example i did on change i get children of the first select in second select
jQuery(document).ready(function($) {
$('.your_select').change(function() {
$.ajaxSetup({
headers:{'X-CSRF-TOKEN': $("meta[name='csrf-token']").attr('content')}
});
$.ajax({
type:'POST',
url: 'Link',
data:{
'id': $(this).val()
},
success:function(r){
$.each(r, function(res) {
console.log(r[res].Nom);
$('.select_to_populate').append($("<option />").val(r[res].id).text(r[res].Nom));
});
},error:function(r) {
alert('Error');
}
});
});
});enter code here
For a newbie like me to JavaScript let alone JQuery, the more JavaScript way of doing it is:
result.forEach(d=>$("#dropdown").append(new Option(d,d)))
I have been using jQuery and calling a function to populate drop downs.
function loadDropDowns(name,value)
{
var ddl = "#Categories";
$(ddl).append('<option value="' + value + '">' + name + "</option>'");
}
Below is the Jquery way of populating a drop down list whose id is "FolderListDropDown"
$.getJSON("/Admin/GetFolderList/", function(result) {
for (var i = 0; i < result.length; i++) {
var elem = $("<option></option>");
elem.attr("value", result[i].ImageFolderID);
elem.text(result[i].Name);
elem.appendTo($("select#FolderListDropDown"));
}
});
You can create options from SQL side (coalesce) and return as string and append that string to drop-down You can remove loop in the code. Ie, if you are using any back end like SQL server You can create options tag using coalesce Ie you will get a string containing entire option
Then you can return the entire string from back end and append to your drop-down
