Pretty new to Javascipt.
Using a form with on top of the form a image. If they change an option in one of the eight dropdown boxes the image will change. However, if they make a configuration that doesn't exsist, the image is not found and the standard broken imagelink will be displayed.
Is there a way to check when I'm changing a value and trigger the onChange="swapImage()"from a dropdown to trigger an event to check if image exsists, and if not, replace it with an error image?
<script type="text/javascript">
function swapImage(){
var image = document.getElementById("imageToSwap");
var hoogte = document.getElementById("hoogte").value;
var bt = document.getElementById("bt").value;
var fase = document.getElementById("fase").value;
var aardlek = document.getElementById("aardlek").value;
var kook = document.getElementById("kook").value;
var groepen = document.getElementById("groepen").value;
var merk = document.getElementById("merk").value;
image.src = "http://www.groepenkasten.expert/images/" + merk + "/" + hoogte + "_" + bt + "_" + fase + "_" + aardlek + "_" + kook + "_" + groepen +".gif";
};
Because the image is Dynamic, there is no full page reload,. Therefore it will not detect the error that the broken image produce when the image doesn't exsist.
Link to the form: http://www.groepenkasten.expert/meld-uw-storing/kant-en-klare-groepenkasten
Related
Context
I've used the "Intersection Observer API" to build an infinite scroll image gallery. Basically this API allows me to load more items when a certain dummy DOM element enters the viewport.
Prototype
Currently the prototype is implemented for an “iPhone X” (375x812) mobile device only. See: http://urbexco-acceptance.droppages.com/min_rep_ex_working (use Chrome DevTools 'inspect' device toolbar to select the right resolution). The image gallery is generated based on 57 items in the "database". When scrolling down, first 15 elements are loaded, then 15 more elements are loaded, then another 15 elements are loaded into the DOM, then another 10 elements are loaded, and finally 2 elements are loaded. When there are still more than 15 items left to be loaded, they are added using the following logic:
function addItems(n){
// Append new items to .items-wrapper
var items = document.querySelector('.items-wrapper');
for (var i = 0; i < n; i++) {
var url = 'https://img01.ztat.net/article/spp-media-p1/09742e38c25b3e1d9716e02f8e76e87d/89fc0bda6a2c446a8e9e0d8adbc9a4fe.jpg';
width = 170.5;
height = 246;
var newDiv = document.createElement('div');
newDiv.classList.add('item');
items.appendChild(newDiv);
newDiv.innerHTML = "<img src=" + '"' + url + '"' + "width=" + '"' + width + '"' + "height=" + height + "/>";
}
}
Minimal Working Example (no mobile view possible)
https://jsfiddle.net/9jqgzymo/
Objective
Since image width and height are currently hardcoded, I am now trying to assign width and height dynamically based on the image url. I try to achieve this using the getMeta() function:
function addItems(n){
// Append new items to .items-wrapper
var items = document.querySelector('.items-wrapper');
for (var i = 0; i < n; i++) {
var url = 'https://img01.ztat.net/article/spp-media-p1/09742e38c25b3e1d9716e02f8e76e87d/89fc0bda6a2c446a8e9e0d8adbc9a4fe.jpg';
getMeta(url);
}
}
function getMeta(url){
var img = new Image();
img.onload = function(){
res = calculateAspectRatioFit(this.width, this.height, 170.5, 246)
var newDiv = document.createElement('div');
newDiv.classList.add('item');
var items = document.querySelector('.items-wrapper');
items.appendChild(newDiv);
newDiv.innerHTML = "<img src=" + '"' + url + '"' + "width=" + '"' + res.width + '"' + "height=" + res.height + "/>";
};
img.src = url;
}
function calculateAspectRatioFit(srcWidth, srcHeight, maxWidth, maxHeight) {
var ratio = Math.min(maxWidth / srcWidth, maxHeight / srcHeight);
return { width: srcWidth*ratio, height: srcHeight*ratio };
}
Challenge
When implementing it this way, I see that - on initiation - already 30 items from the "database" where added to the DOM. Sometimes even all of them? Currently the non-working prototype is implemented for an “iPhone X” (375x812) mobile device only. See: http://urbexco-acceptance.droppages.com/min_rep_ex_not_working (use Chrome DevTools 'inspect' device toolbar to select the right resolution). For a minimal working example, see: https://jsfiddle.net/k3p20qno/
Key question
What is the reason that with my new implementation, on initiation, already 30 or more items are added to the DOM? How can I fix it?
Well the problem lies in here :
function getMeta(url){
var img = new Image();
img.onload = function(){
res = calculateAspectRatioFit(this.width, this.height, 170.5, 246)
var newDiv = document.createElement('div');
newDiv.classList.add('item');
var items = document.querySelector('.items-wrapper');
items.appendChild(newDiv);
newDiv.innerHTML = "<img src=" + '"' + url + '"' + "width=" + '"' + res.width + '"' + "height=" + res.height + "/>";
};
img.src = url;
}
Above code does an async operation with onload event. So it doesn't wait to image to be loaded.
If you turn this into a function that returns a promise you will get the result that you expect. And you should await where you call the function. That way when you add the intersection element it will add it as the last element of the items wrapper. If you don't await it will be added as the first element because the loading of the images will be async and will happen later.
function getMeta(url){
var img = new Image();
const p = new Promise(resolve =>{
img.onload = function(){
console.log( this.width+' '+ this.height );
res = calculateAspectRatioFit(this.width, this.height, 170.5, 246)
var newDiv = document.createElement('div');
newDiv.classList.add('item');
var items = document.querySelector('.items-wrapper');
items.appendChild(newDiv);
newDiv.innerHTML = "<img src=" + '"' + url + '"' + "width=" + '"' + res.width + '"' + "height=" + res.height + "/>";
resolve()
};
})
img.src = url;
return p;
}
Fiddle
Edit: Put the resolve() in the right position which is inside the load function
I have a code that puts images on a table(html), and I want to focus on the image that has just appeared.
I know that i have to use $(this) but i don't know how, here is my code
function positioning(year, mon) {
$('#' + year + ' .' + mon).prepend('<img class="black_point" src="./images/circle.png"/>');//that adds the image
var table = document.getElementById("table");
var images = table.getElementsByTagName("img");
//here I need the current image I had just add to send to that function
function connect(images) {
var tabBcr = table.getBoundingClientRect();
var imgBcr = image.getBoundingClientRect();
x = imgBcr.left + (imgBcr.width / 2) - tabBcr.left;
y = imgBcr.top + (imgBcr.height / 2) - tabBcr.top;
}
}
I hope I have explained well .
I think it will work, add this where you want to get that img element:
var imgelem=$('#' + year + ' .' + mon).find("img:first");
I've got the following code that produces a dynamically created image button and panel in asp.net: -
Panel panBlocks = new Panel();
panBlocks.ID = "PanBlockQuestionID" + recordcount.ToString();
panBlocks.Width = 1300;
panBlocks.Height = 50;
panBlocks.BackColor = Color.Pink;
ImageButton cmdBlocks = new ImageButton();
cmdBlocks.ImageUrl = "~/Images/block3.png";
cmdBlocks.ID = "lblImg" + recordcount.ToString();
cmdBlocks.Attributes["class"] = "liQuestionsLabel2";
cmdBlocks.Width = 30;
cmdBlocks.Attributes.Add("OnMouseOver", "showPanel(" + "CPH_Body_" + panBlocks.ClientID.ToString() + ")");
cmdBlocks.Attributes.Add("OnMouseOut", "hidePanel();");
li.Controls.Add(cmdBlocks);
li.Controls.Add(panBlocks);
When I hover over the image I want it to display a particular panel. I've added the "CPH_Body_" + panBlocks.ClientID.ToString() as an attribute.
I've got the following javascript code:
function showPanel(PanelID)
{
document.getElementById("CPH_Body_liQuestions1").style.height = "40px";
}
How do I retrieve the PanelID in the javascript please as it looks like an array. I need to retrieve this so I know which panel to display please.
IIUC (!!):
Change this :
cmdBlocks.Attributes.Add("OnMouseOver", "showPanel(" + "CPH_Body_" + panBlocks.ClientID.ToString() + ")");
To:
cmdBlocks.Attributes.Add("OnMouseOver", "showPanel('" + panBlocks.ClientID.ToString() + "')");
And change this :
function showPanel(PanelID)
{
document.getElementById("CPH_Body_liQuestions1").style.height = "40px";
}
To
function showPanel(PanelID)
{
document.getElementById(PanelID).style.height = "40px";
}
I'm working with markers on google map and this is what happens
I call this variable to the images and upload to the database and use a query to put two images into a single file (GROUP_CONCAT)
var image = markers[i].getAttribute("image");
image = image.split(",");
And here I show these pictures.
var html = div id = "iw-container" +
'a Href="'+image[0]+'" data-lightbox="roadtrip" <img src = "' + image [0] +" "width = 100" height = "100" / a '+
'a Href="'+image[1]+'" data-lightbox="roadtrip" <img src = "' + image [1] + '" width = 100 "height =" 100 " / a '+
'a Href="'+image[2]+'" data-lightbox="roadtrip" <img src = "' + image [2] + '" width = 100 "height =" 100 " / a '+
'/ Div';
The problem is if a marker is less than 3 images, for example a marker has 2 images, one of the images appear broken. obviously because not defined. ()
I wonder if there is any function or something to check if an image has the "SRC" undefined, remove it or hide it or do something to not appear.
Any help is good, thanks :)
Code like this should get you past this issue:
var html = '';
for(var i=0;i < image.length; i++) {
html += image[i];
}
I am trying to populate a div (class='thumb") with thumnailpictures. The name of the pictures is gathered from an xml file. Every thumnail picture is encapsulated with an a-tag that points to a function to show the full picture.
On some browsers the first thumbnailpicture seems not to have this a-tag...clicking on it gives no action...
var rubriek = gup('rubriek'), // rubriek is a parameter in the url of this page pointing a specific photogallery
gallerij = rubriek + "gallery.xml",
xmlDoc = loadXMLDoc(gallerij),
x = xmlDoc.getElementsByTagName("filename"),
legebron = x[0].childNodes[0].nodeValue;
for (i = 0; i < x.length; i++) {
var beeldnummer = x[i].childNodes[0].nodeValue,
index = i + 1,
kleinbeeld = "/" + rubriek + "images/thumb/" + beeldnummer;
$('.thumb').append('<p><a class="kleintje" onclick="toonDezeFoto("' + beeldnummer + '",' + index + ',' + x.length + ');">
<img src="' + kleinbeeld + '" id="' + index + '">
</a></p>');
}
See http://www.karinedaelman.be/foto.php?rubriek=Mensen/
Found the solution: the z-index of the div that keeps the thumbnails was too low. Another div that has the site logo in it had a higher z-index and a width of 100%. Because of that the first thumbnail image was on a layer below the site logo and could not be accessed by the mouseevents....