I read from this page that appending a lot of elements is bad practice and I should build up a string during each iteration of the loop and then set the HTML of the DOM element to that string. Does the same go for using too much HTML in the loop?
I have an AJAX script that parses JSON data. It requires adding data to different existing elements, like this:
$.ajax({
url: "url",
success: function (data) {
$(data.query.results.json.json).each(function (index, item) {
var title = item.title, // A,B,C or D
age = item.age,
background = item.background,
ingredient = item.Ingredient;
$('.'+ title+'_ingredient').html(''+ingredient+'')
$('.'+ title+'_age').html(''+age+'')
$('.'+ title+'_background').html(''+background+'')
});
},
error: function () {}
});
HTML:
<div class="A_ingredient"></div>
<div class="B_ingredient"></div>
<div class="C_ingredient"></div>
<div class="D_ingredient"></div>
<div class="A_age"></div>
<div class="B_age"></div>
<div class="C_age"></div>
<div class="D_age"></div>
<div class="A_background"></div>
<div class="B_background"></div>
<div class="C_background"></div>
<div class="D_background"></div>
Is it necessary to build up a string first? If so, can you show me how to do that?
It is purely about the time it takes to process calls to html() so they simply recommend you reduce the number of calls. In this case you could build them once in a loop then sets the div html once for each.
Update:
Based on your update, aside from all the extra trailing quotes you don't need to add (a string is a string is a string), your code is fine as is. You only hit each item once.
e.g.
$.ajax({
url: "url",
success: function (data) {
$(data.query.results.json.json).each(function (index, item) {
var title = item.title, // A,B,C or D
age = item.age,
background = item.background,
ingredient = item.Ingredient;
$('.'+ title+'_ingredient').html(ingredient);
$('.'+ title+'_age').html(age);
$('.'+ title+'_background').html(background);
});
},
error: function () {}
});
Note: If your item properties (Age, Background, Ingredient) are simple values (not objects or arrays), yo do not need the leading ''+s either.
Previous
Assuming you actually want to concatenate the results (you are only keeping the last ingredient at the moment), you could do something like this:
e.g.
$.ajax({
url: "url",
success: function (data) {
var ingredients = '';
$(data.query.results.json.json).each(function (index, item) {
var title = item.title;
var ingredient = item.Ingredient;
ingredients += ingredient;
});
$('.aclass').html(ingredients);
$('.bclass').html(ingredients);
$('.cclass').html(ingredients);
$('.dclass').html(ingredients);
},
error: function () {}
});
Which can be reduced to:
$('.aclass,.bclass,.cclass,.dclass').html(ingredients);
The contents of each div are identical in your example, so you only need a single string.
In this instance you would probably need some form of delimiter between ingredients, but your example is too vague.
e.g.
ingredients += ingredient + '<br/>';
In your example, you're setting the HTML on many different document elements.
If they're grouped in some way, for example all in a Div with ID #Container, you could build a string of the HTML and set the content of the whole Div at the end of it, something like this:
$.ajax({
url: "url",
success: function (data) {
var sHTML="";
$(data.query.results.json.json).each(function (index, item) {
var title = item.title,
background = item.background,
ingredient = item.Ingredient;
// not sure what your actual HTML is (div/span/td etc) but somethign like this?
sHTML+="<div>"; // an opening container for this item
sHTML+='<div class="'+title+'_ingredient">'+ingredient+'</div>')
sHTML+='<div class="'+title+'_age">'+title+'</div>')
sHTML+='<div class="'+title+'_background">'+background+'</div>')
sHTML+="</div>";
});
$("#Container").html(sHTML);
},
error: function () {}
});
Note I haven't tested this code, but you see the principal hopefully.
That is, build a string of the HTML then set one element at the end with the content.
I have done this a lot in a recent project and haven't seen any speed issues (maybe 50 'items' to set in my case).
HTML will initially look like this :
<div id="container">
</div>
Then end up like this (2 x items in this example) :
<div id="container">
<div>
<div class="<sometitle1>_ingredient">ingredient 1</div>
<div class="<sometitle1>_age">age 1</div>
<div class="<sometitle1>_background">background 1</div>
</div>
<div>
<div class="<sometitle2>_ingredient">ingredient 2</div>
<div class="<sometitle2>_age">age 2</div>
<div class="<sometitle2>_background">background 2</div>
</div>
</div>
subsequent calls will replace the element's content with new values, replacing the old items.
Building a string is, I would imagine, less processor-heavy than setting the html() on lots of elements individually. Each time you use html() I'm guessing that the browser has to go some way towards working out any knock-on effects like expanding the width of an element to accomodate it or whether events will still work as they did, etc - even if actual rendering is only run at the end of the process. This way you use html() once, although what you're setting is more complex.
Hope this helps.
Related
I've been getting crazier day after day with this, I can't find an answer, I've spent like 100h+ with this... I hope someone could help me out!
UPDATE:
So to make myself more clear on this issue and be able to get help from others, I basically have 3 containers named "main-container" they all have 3 containers as childs all with the same class name, and when I submit the button, I trigger an ajax function to load the JSON strings comming from php into the child divs, the problem is that I get the 3 "main_containers" to load the ajax at the same time, I only want to load the ajax if I press the button of each "main_container" individually.
I've been using jquery and vanilla JS as well but seems I just can't get it done!
This is how I currently trigger the button with jquery:
$('.trigger_button_inside_divs').click(my_ajax_function);
And this is how my ajax looks like:
function my_ajax_function(){
$.ajax({
dataType: "JSON",
type: 'POST',
url: test.php,
success: function(data) {
$('.div_to_render_JSON_1').html(data.PHP_JSON_1_RECEIVED);
$('.div_to_render_JSON_2').html(data.PHP_JSON_2_RECEIVED);
$('.div_to_render_JSON_3').html(data.PHP_JSON_3_RECEIVED);
}
});
}
HTML looks like this:
<div class="main_container">
<div class="my_div">
//div_to_render_JSON_1
</div>
<div class="my_div">
//div_to_render_JSON_2
</div>
<div class="my_div">
//div_to_render_JSON_3
</div>
<button class="trigger_ajax_function_btn">Click to load ajax</button> //this btn loads ajax into the div class "my_div"
</div>
<div class="main_container">
<div class="my_div">
//div_to_render_JSON_1
</div>
<div class="my_div">
//div_to_render_JSON_2
</div>
<div class="my_div">
//div_to_render_JSON_3
</div>
<button class="trigger_ajax_function_btn">Click to load ajax</button> //this btn loads ajax into the div class "my_div"
</div>
<div class="main_container">
<div class="my_div">
//div_to_render_JSON_1
</div>
<div class="my_div">
//div_to_render_JSON_2
</div>
<div class="my_div">
//div_to_render_JSON_3
</div>
<button class="trigger_ajax_function_btn">Click to load ajax</button> //this btn loads ajax into the div class "my_div"
</div>
So in conclusion, each of those 6 "divs" has a button that triggers an function containing my ajax to render inside that particular div. But what I get is that every time I click that triggering button, I get the ajax to render in all of the 6 divs, instead of render on each particular div only when I click its particular button.
Thanks a lot people, I really hope to get this done!
Cheers.
PD:
This is something a programmer did to achieve what I'm trying to achieve but I just can't figure out what in this code is that is making possible clicking 1 button and affect THAT html element , even though they all have the same class.
(function(){
$("form input[type=submit]").click(function() {
$("input[type=submit]", $(this).parents("form")).removeAttr("clicked");
$(this).attr("clicked", "true");
});
var xhr = new XMLHttpRequest();
var el;
function SetDataInTheForm()
{
var resp = JSON.parse(xhr.response)
var pt=0
var ct=0
var gt=0
Array.prototype.forEach.call(el.querySelectorAll(".test"),function(e,i){
e.innerHTML=resp[i].name
})
Array.prototype.forEach.call(el.querySelectorAll(".p"),function(e,i){
e.innerHTML=parseFloat(resp[i].p).toFixed(0)
pt+=parseFloat(resp[i].p)
})
Array.prototype.forEach.call(el.querySelectorAll(".c"),function(e,i){
e.innerHTML=parseFloat(resp[i].c).toFixed(0)
ct+=parseFloat(resp[i].c)
})
Array.prototype.forEach.call(el.querySelectorAll(".g"),function(e,i){
e.innerHTML=parseFloat(resp[i].g).toFixed(0)
gt+=parseFloat(resp[i].g)
})
el.querySelector(".wtp").innerHTML=parseFloat(resp[0].total).toFixed(0)+" "+resp[0].unit
el.querySelector(".wtc").innerHTML=parseFloat(resp[1].total).toFixed(0)+" "+resp[1].unit
el.querySelector(".wtg").innerHTML=parseFloat(resp[2].total).toFixed(0)+" "+resp[2].unit
el.querySelector(".pt").innerHTML=pt.toFixed(0)
el.querySelector(".ct").innerHTML=ct.toFixed(0)
el.querySelector(".gt").innerHTML=gt.toFixed(0)
}
function HandleSubmit(e)
{
el=e.currentTarget
e.preventDefault();
xhr.open("POST","/url_here.php",true)
xhr.setRequestHeader("content-type","application/x-www-form-urlencoded")
xhr.onload=SetDataInTheForm
var button=e.currentTarget.querySelector("input[type=submit][clicked=true]")
button.removeAttribute("clicked")
xhr.send($("#"+e.currentTarget.id).serialize()+"&"+button.getAttribute("name")+"=on")
}
[].forEach.call(document.querySelectorAll("._form_"),function(form){
form.addEventListener("submit",HandleSubmit,false);
})
})()
Remember that $('.div_container_to_render_JSON') is a new selector that selects all elements with a class div_container_to_render_JSON. What you want to happen is figuring out where that click came from, and find the corresponding div_container_to_render_JSON.
Luckily for you, a jQuery click handler sets the this keyword to the HTMLElement where the click was captured. You can use this to get the parent element.
$('.your-button').on('click', function () {
const myButton = $(this);
$.ajax({
// ...
success (data) {
myButton.parent().html(data.PHP_JSON_RECEIVED);
// or if you need to find a parent further up in the chain
// myButton.parents('.div_container_to_render_JSON').html(data.PHP_JSON_RECEIVED);
}
});
});
The problem is that your class selector is indeed selecting all your divs at the same time.
Solution, set identifiers for your divs as such:
<div class="my_div" id="my_div_1">
and then you can use those id's to fill in the data:
$('#my_div_1').html(data.PHP_JSON_1_RECEIVED);
and repeat for your 6 divs (notice the change from class selector '.' to identifier selector '#')
Thanks for the replies people. I finally figured it out after days of hard work, it was something really simple.. here's the answer:
$('.trigger_button_inside_divs').click(my_ajax_function);
var thisButton = $(this);
var thisDiv = thisButton.closest(".main_container");
function my_ajax_function(){
$.ajax({
dataType: "JSON",
type: 'POST',
url: test.php,
success: function(data) {
thisDiv.find('.div_to_render_JSON_1').html(data.PHP_JSON_1_RECEIVED);
thisDiv.find('.div_to_render_JSON_2').html(data.PHP_JSON_2_RECEIVED);
thisDiv.find('.div_to_render_JSON_3').html(data.PHP_JSON_3_RECEIVED);
}
});
}
I am currently coding within a ViewComponent (ViewComponent1) view. Within this View, I have listed a few items:
As you can see, the channels 11, 12, 13 and 14 are clickable. Each channel has some additional information (OBIS, avtalsid.. etc). What I´m trying to do is to invoke ViewComponent2, within ViewComponent1, and pass along some of the data, based on the clicked item.
What I tried to do is to create another View called "Test" and within that View invoke ViewComponent2 along with its parameters, like this:
<div class="row">
<div class="col-md-2 canalstyle">
<a asp-controller="Customer" asp-action="Test" asp-route-pod="#item.STATION"
asp-route-idnr="#item.IDNR" asp-route-kanal="#item.KANAL" asp-route-start="#Model.start"
asp-route-end="#Model.end"> #Html.DisplayFor(modelItem => item.KANAL)</a>
</div>
</div>
This works, but this method redirects me away from my current View (ViewComponent 1). I don't want that. I want the current view to load the additional information from ViewComponent2.
My function that runs the ajax:
function myFunction() {
var data = JSON.stringify({
'idnr': id,
'start': this.start,
'end': this.end
});
$.ajax({
url: '#Url.Action("Test2","Customer")',
type: 'GET',
data: { idnr: id, start: this.start, end: this.end },
contentType: 'application/json',
success: handleData(data)
})
};
function handleData(data) {
alert(data);
var url = $(this).attr("href");
var $target = $(this).closest("div").find(".details");
$.get(url, function (res) {
$target.html(res);
});
//do some stuff
}
And my Test2 Action:
public async Task<IActionResult> Test2(string idnr, string start, string end)
{
ServiceClient r2s = new R2S.ServiceClient();
R2S.Konstant[] kData = r2s.GetKonstantListAsync(new string[] { "IDNR" }, new string[] { idnr}).Result; // mätarnummer in... --> alla konstanter kopplade till denna.
return ViewComponent("MeterReader2", new { k = kData[0], start = start, end = end });
}
I am trying to target the same DOM.. Any ideas?
Your current code is rendering links (a tags) and normally clicking on a link will do a new GET request, which is what you are seeing , the redirect to the new action method.
If you do not want the redirect, but want to show the result of the second view component in same view, you should use ajax.
For example, If you want to show the result of second view component just below each link, you may add another html element for that. Here i am adding an empty div.
<div class="row">
<div class="col-md-2 canalstyle">
<a class="myClass" asp-controller="Customer" asp-action="DetailsVc"
asp-route-id="#item.Id" > #item.KANAL</a>
<div class="details"></div>
</div>
</div>
Here i just removed all those route params you had in your orignal question and replaced only with on param (id) . Assuming your items will have an Id property which is the unique id for the record(primary key) and using which you can get the entity (from a database or so) in your view component to get the details.
This will generate the link with css class myClass. You can see that, i used asp-action attribute value as "DetailsVc". We cannot directly use the view component name in the link tag helper as attribute value to generate the href value. So we should create a wrapper action method which returns your view component result such as below
public IActionResult DetailsVc(int id)
{
return ViewComponent("DetailsComponent", new { id =id });
}
Assuming your second view components name is DetailsComponent and it accepts an id param. Update the parameter list of this action method and view component as needed. (but i suggest passing just the unique Id value and get details in the server code again)
Now all you have to do is have some javascript code which listen to the click event on those a tags and prevent the normal behavior (redirect) and make an ajax call instead, use the ajax call result to update the details div next to the clicked link.
You can put this code in your main view (or in an external js file without the #section part)
#section Scripts
{
<script>
$(function() {
$("a.myClass").click(function(e) {
e.preventDefault();
var url = $(this).attr("href");
var $target = $(this).closest("div").find(".details");
$.get(url,function(res) {
$target.html(res);
});
});
});
</script>
}
I have html code with data from database. I need to update this data via AJAX, so users get the new currency rates without page refresh. Here's Laravel blade template:
#foreach ($currencies as $currency)
<div class="currency-{{ $currency->id }}">
<div class="cur-id">{{ $currency->id }}</div>
<div class="cur-name">{{ $currency->cur_name }}</div>
<div class="cur-sell">{{ $currency->cur_sell + 0 }}</div>
<div class="cur-buy">{{ $currency->cur_buy + 0 }}</div>
</div>
#endforeach
Once the page is loaded - it has actual data, but after 1 minute this data being refreshed, so i am firing an AJAX request every minute:
$.ajax({
type: 'GET',
url: '/ajax-currencies',
dataType: 'json',
success: function (data) {
$.each(data, function(index, element) {
$('.currency-+element.id+.cur-sell').text(element.cur_sell);
});
}
});
"/ajax-currencies" responses with json objects. How can i put each object with its values in to correct div - currency-1 (has own values), currency-2 (has own values) etc, so it looks like this:
<div class="currency-1">
<div class="cur-id">1</div>
<div class="cur-name">Bitcoin</div>
</div>
<div class="currency-2">
<div class="cur-id">2</div>
<div class="cur-name">Ethereum</div>
</div>
I don't know why you need any kind of sorting. If your divs have special classes, then you can find divs by these classes and insert data directly in these divs. You're already trying to do this, but incorrect. Your each callback should be:
function(index, element) {
$('.currency-' + element.id + ' .cur-sell').text(element.cur_sell);
// alternative version
//$('.currency-' + element.id).find('.cur-sell').text(element.cur_sell);
}
See, I moved element.id out of quoted string, as javascript cannot parse variables inside quoted strings.
I also added a space between classes in selector, because selector like .class1.class2 will try to find item with both classes applied, which you don't want.
Also, I added alternative selector using find() method. Just for example.
Now the selector should select correct div.
I'm having trouble populating a SELECT with jquery, when the user writes the zipcode or part of it, it searches the database and returns this:
{"success":1,"id":"50","street":"Central One"},{"success":1,"id":"60","street":"Central Two"}
One success for each street it finds. For a single street and using a text input I'm using this
UPDATE 1 - FULL CODE
$(document).ready( function() {
$('#zip').blur(function(){
$.ajax({
url : '../../controller/zip.php',
type : 'POST',
data: 'zip=' + $('#zip').val(),
dataType: 'json',
success: function(data){
if(data.sucesso == 1){
$('#id').val(data.id);
$('#street').val(data.street);
}
}
});
return false;
})
});
How can I change this so I can populate a select box.
Thanks
What is being passed back for a single address is a single object from which you can grab the information. When there are multiple responses you need to go through each of them and handle them.
When we look at MDN's article it shows that we need a parent <select> tag and then we need to populate the children. The process would look like this:
Find / create parent select
[Optional] Remove previous child <option> tags
Loop through responses
Create a new <option> element
Populate the <option> with the appropriate value and content
Append it to the parent <select>
Some things to be aware of, if you're clearing the previous addresses each time you get a response from the database you'll want to remove these previous <option>s. This can be done either by .empty() if there are no other children in the parent or starting with the parent <select> and removing all child <options>.
Use this for adding items to select box dynamically:
var $selectBox = $('#selectboxId');
$selectBox.empty();
$.each(data, function (idx, val) {
if (val.success) {
$selectBox.append($('<option>', {
value: val.id,
text: val.street
}));
}
});
I would not encourage to do so; you're better off using a html-templating engine like mustache or handlebars.
Doing this kind of stuff in plain JS (string concatenation) is gross. It pollutes your sourcecode.
Anyways, this would do the trick to generate the necessary HTML:
function generateHTML(data){
return data.reduce(function(o,n){
return o+"<option value='"+n.id+"'>"+n.street+"</option>";
},"");
}
Here is the Fiddle to play with. If you need to filter for success, you could add a filter()
function generateHTML(data){
return data.filter(function(x){
return !!x.success;
}).reduce(function(o,n){
return o+"<option value='"+n.id+"'>"+n.street+"</option>";
},"");
}
You could easily use $("#selectBoxId").html(generateHTML(data)) to insert it to the DOM.
To fit it into your codebase, you should add it in the success handler:
success: function(data){
function generateHTML(data){
return data.reduce(function(o,n){
return o+"<option value='"+n.id+"'>"+n.street+"</option>";
},"");
}
$("select").html(generateHTML(data))
}
For the inner workings of Array.prototype.reduce() take a look at MDN and for Array.prototype.filter()
If the JSON being returned is a list [{...}, ..., {...}], then you can use Array.forEach. Here is the success callback:
function(data) {
data.forEach(function(item) {
if (item.success) {
// use item.id and item.street
}
});
}
If you have a <select> element, then you will want to be populating it with <options>, by appending an <option> element under each successful "if" branch in the forEach.
Assuming you already have the select element on the page and the data that is coming back from the server is an array of objects, this should work:
$.ajax({
url : '../../controller/zip.php',
type : 'POST',
data: 'zip=' + $('#zip').val(),
dataType: 'json',
success: function(data) {
var $items = [];
$.each(data, function(street) {
if(data.success === 1) {
$items.push($('<option />').attr({
value: street.id
}).text(street.street));
}
});
$('#your-select-element').append($items);
}
});
Notice this isn't setting the value for one option, it is creating <option> tags for each of the response's streets and appending them to a <select> element.
I have a text field which uses select2. Here is the initialization:
$("#foo").select2({
createSearchChoice:function(term, data) {
if ($(data).filter(function() {
return this.text.localeCompare(term)===0;
}).length===0)
{return {id:term, text:term};}
},
initSelection : function (element, callback) {
var data = {id: element.val(), text: element.val()};
callback(data);
},
tags:[],
tokenSeparators: [","],
data: [...data goes here...]
});
In this field, the user is supposed to put in a number, or select items from a list. If an item that the user puts in doesn't appear on the list, it ought be created as a simple tag (id and text identical). This works.
What doesn't work is when I set the value programmatically:
myvar.find('.placeholder lorem-ipsum').val(number).trigger("change");
The way it works now, is that when I set it to any value, it takes it without complaint, making a new simple tag. However, if I were to remove the initSelection parameter completely, it would ignore unknown values, and use known values as taken from the list (where tags are complex - id and text are different).
How do I make it so that if the value I set to the field is found on the list, it will use the item, and otherwise make a simple tag? The way it works now (simple tags only) is sort-of acceptable, but I'd prefer it worked ideally.
EDIT:
I've made examples for how it works with and without the initSelection parameter.
http://jppk.byethost12.com/with.html
http://jppk.byethost12.com/without.html
In short, I want it to work like with.html when I push "Add New Item" and I want it to work like without.html when I push "Add Existing Item".
Here is my best interpretation of what you want.
JSFiddle
The trick is to append the element to the select field.
var array = ['foo', 'bar', 'baz']
$.each(array, function(key, value) {
appendSelect(value);
});
$("#foo").select2();
$('#submit').click(function() {
var val = $('#name').val();
$('#name').val('');
array.push(val);
appendSelect(val);
});
function appendSelect(value) {
$('#foo').append($("<option></option>").text(value));
}
<link href="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0-rc.1/css/select2.min.css" rel="stylesheet" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0-rc.1/js/select2.min.js"></script>
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" rel="stylesheet">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js"></script>
<div class='container'>
<select id='foo' multiple="multiple" class='form-control'></select>
<label>Input</label>
<input id='name' />
<button id='submit'>submit</button>
</div>
Much, much later, I found a solution that works right:
initSelection : function (element, callback) {
var eArr = element.val().split(",");
var data = [];
for (var i=0;i<eArr.length;i++) {
for (var j=0;j<preExistingData.length;j++) {
if (preExistingData[j]["id"] === eArr[i]) {
data.push(preExistingData[j]);
continue;
}
}
data.push({id: eArr[i], text: eArr[i]});
}
callback(data);
},
This not only checks if the value is among the pre-existing values (in which case it uses that item), but also if the value is a comma-separated list of values (in which case it properly encapsulates them as JS objects).