Javascript img not found

Resource loading: onload and onerror

The browser allows us to track the loading of external resources – scripts, iframes, pictures and so on.

There are two events for it:

Loading a script

Let’s say we need to load a third-party script and call a function that resides there.

We can load it dynamically, like this:

let script = document.createElement('script'); script.src = "my.js"; document.head.append(script);

…But how to run the function that is declared inside that script? We need to wait until the script loads, and only then we can call it.

For our own scripts we could use JavaScript modules here, but they are not widely adopted by third-party libraries.

script.onload

The main helper is the load event. It triggers after the script was loaded and executed.

let script = document.createElement('script'); // can load any script, from any domain script.src = "https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.3.0/lodash.js" document.head.append(script); script.onload = function() < // the script creates a variable "_" alert( _.VERSION ); // shows library version >;

So in onload we can use script variables, run functions etc.

…And what if the loading failed? For instance, there’s no such script (error 404) or the server is down (unavailable).

script.onerror

Errors that occur during the loading of the script can be tracked in an error event.

For instance, let’s request a script that doesn’t exist:

let script = document.createElement('script'); script.src = "https://example.com/404.js"; // no such script document.head.append(script); script.onerror = function() < alert("Error loading " + this.src); // Error loading https://example.com/404.js >;

Please note that we can’t get HTTP error details here. We don’t know if it was an error 404 or 500 or something else. Just that the loading failed.

Events onload / onerror track only the loading itself.

Errors that may occur during script processing and execution are out of scope for these events. That is: if a script loaded successfully, then onload triggers, even if it has programming errors in it. To track script errors, one can use window.onerror global handler.

Other resources

The load and error events also work for other resources, basically for any resource that has an external src .

let img = document.createElement('img'); img.src = "https://js.cx/clipart/train.gif"; // (*) img.onload = function() < alert(`Image loaded, size $x$`); >; img.onerror = function() < alert("Error occurred while loading image"); >;

There are some notes though:

• Most resources start loading when they are added to the document. But is an exception. It starts loading when it gets a src (*) .
• For , the iframe.onload event triggers when the iframe loading finished, both for successful load and in case of an error.

That’s for historical reasons.

Crossorigin policy

There’s a rule: scripts from one site can’t access contents of the other site. So, e.g. a script at https://facebook.com can’t read the user’s mailbox at https://gmail.com .

Or, to be more precise, one origin (domain/port/protocol triplet) can’t access the content from another one. So even if we have a subdomain, or just another port, these are different origins with no access to each other.

This rule also affects resources from other domains.

If we’re using a script from another domain, and there’s an error in it, we can’t get error details.

For example, let’s take a script error.js that consists of a single (bad) function call:

Now load it from the same site where it’s located:

We can see a good error report, like this:

Uncaught ReferenceError: noSuchFunction is not defined https://javascript.info/article/onload-onerror/crossorigin/error.js, 1:1

Now let’s load the same script from another domain:

The report is different, like this:

Details may vary depending on the browser, but the idea is the same: any information about the internals of a script, including error stack traces, is hidden. Exactly because it’s from another domain.

Why do we need error details?

There are many services (and we can build our own) that listen for global errors using window.onerror , save errors and provide an interface to access and analyze them. That’s great, as we can see real errors, triggered by our users. But if a script comes from another origin, then there’s not much information about errors in it, as we’ve just seen.

Similar cross-origin policy (CORS) is enforced for other types of resources as well.

To allow cross-origin access, the tag needs to have the crossorigin attribute, plus the remote server must provide special headers.

There are three levels of cross-origin access:

1. No crossorigin attribute – access prohibited.
2. crossorigin=»anonymous» – access allowed if the server responds with the header Access-Control-Allow-Origin with * or our origin. Browser does not send authorization information and cookies to remote server.
3. crossorigin=»use-credentials» – access allowed if the server sends back the header Access-Control-Allow-Origin with our origin and Access-Control-Allow-Credentials: true . Browser sends authorization information and cookies to remote server.

You can read more about cross-origin access in the chapter Fetch: Cross-Origin Requests. It describes the fetch method for network requests, but the policy is exactly the same.

Such thing as “cookies” is out of our current scope, but you can read about them in the chapter Cookies, document.cookie.

In our case, we didn’t have any crossorigin attribute. So the cross-origin access was prohibited. Let’s add it.

We can choose between «anonymous» (no cookies sent, one server-side header needed) and «use-credentials» (sends cookies too, two server-side headers needed).

If we don’t care about cookies, then «anonymous» is the way to go:

Now, assuming that the server provides an Access-Control-Allow-Origin header, everything’s fine. We have the full error report.

Summary

Images , external styles, scripts and other resources provide load and error events to track their loading:

The only exception is : for historical reasons it always triggers load , for any load completion, even if the page is not found.

The readystatechange event also works for resources, but is rarely used, because load/error events are simpler.

Tasks

Load images with a callback

Normally, images are loaded when they are created. So when we add to the page, the user does not see the picture immediately. The browser needs to load it first.

To show an image immediately, we can create it “in advance”, like this:

let img = document.createElement('img'); img.src = 'my.jpg';

The browser starts loading the image and remembers it in the cache. Later, when the same image appears in the document (no matter how), it shows up immediately.

Create a function preloadImages(sources, callback) that loads all images from the array sources and, when ready, runs callback .

For instance, this will show an alert after the images are loaded:

function loaded() < alert("Images loaded") >preloadImages(["1.jpg", "2.jpg", "3.jpg"], loaded);

In case of an error, the function should still assume the picture “loaded”.

In other words, the callback is executed when all images are either loaded or errored out.

The function is useful, for instance, when we plan to show a gallery with many scrollable images, and want to be sure that all images are loaded.

In the source document you can find links to test images, and also the code to check whether they are loaded or not. It should output 300 .

1. Make img for every source.
2. Add onload/onerror for every image.
3. Increase the counter when either onload or onerror triggers.
4. When the counter value equals to the sources count – we’re done: callback() .

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Html get html image not found javascript

Solution 1: Well, the public directory will be accessible from the root directory and there is no in real life applications, so you need to use absolute path here like this: NOTE: If you did not resolve your public directory in your , you also may need to resolve it like this: Solution 2: Just mess with the path: Solution 3: The same code works for me. This is my attempt : Solution: When you start using nodeJS, you will need to have a proper structure of folders.

HTML image not loading , and I cannot find what is problem

Well, the public directory will be accessible from the root directory and there is no /public in real life applications, so you need to use absolute path here like this:

NOTE: If you did not resolve your public directory in your app.js , you also may need to resolve it like this:

var path = require('path'); app.use(express.static(path.resolve('./public'))); 

./public/images/image.png public/images/image.png images/image.png 

The same code works for me. Will you able to open the image through browser? Which path it is looking for the image? when you refresh the browser you can see it in networks tab

HTML image not loading , and I cannot find what is problem, I tried to load an image file on the HTML code, but it doesn’t work like this. How can I fix this problem? Maybe change the path to /public/

Image not showing up in Html/Javascript

That is the general code for calling the image. Tell me if you need more context/you need me to put the rest of the code in.

Basically You will need to «draw» the image into a canvas. https://www.w3schools.com/tags/canvas_drawimage.asp

Image not showing up in Html/Javascript, Your code is running correctly, the img element is injected at the bottom of the body, which is expected. What’s the problem? – FisNaN

How to fix error file not found when trying to link to an image on javascript

As mention by @Vikas Keskar, you need to use a relative path. Keep the gif file inside the same directory as your html file.

Note: remember to link Jquery inside the html file or this script will not work.

If you want to do it in vanilla JavaScript, here is the code:

If you are going to use vanilla JavaScript instead, make sure to add onclick=»bulb_off()» to your button tag. So your button tag should look like this:

The backslash (\) is an escape character in Javascript (along with a lot of other C-like languages). This means that when Javascript encounters a backslash, it tries to escape the following character. For instance, \n is a newline character (rather than a backslash followed by the letter n).

this what I got in the console when I tried to console your absolute path

console result: C:Users tDesktopWebDevWebpageimagespic_bulboff.gif

this is because backwards in the absolute path.

    and to solve this issue you may for each backslash you want to output, you need to give Javascript two. 

HTML Image not displaying, while the src url works, Make sure, as @William Yang posted, that your image is on the computer that is hosting the website. Pop it into your www folder, and then link

Image not displaying in HTML and Nodejs (404 Not Found)

When you start using nodeJS, you will need to have a proper structure of folders. You need to have a folder called public inside your main project. In public folder, create another folder and name it assets. In assets folder, create another folder and name it images. Then, add all of your images in that images folder.

app.use('/images', express.static('images')); 

app.use(express.static(__dirname + '/public')); 

Then, you can add your images path to html like this

 app.get('/',function(req,res)< res.sendFile(__dirname + '/index.html'); >); 

Html img not found Code Example, Queries related to “html img not found” · if image not found html · html if no image then text · html img if not avaiable · if image not found javascript · if image

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jQuery JS check if img is not found

The following tutorial shows you how to do «jQuery JS check if img is not found».

The result is illustrated in the iframe.

You can check the full source code and open it in another tab using the links.

Javascript Source Code

The Javascript source code to do «jQuery JS check if img is not found» is

var img = $(""); img.on('load', function(e)< console.log('Success!'); >).on('error', function(e) < console.log('ERROR!'); >); img.appendTo("body");

html> head> meta name="viewport" content="width=device-width, initial-scale=1"> script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" >  body> script type='text/javascript'> var img = $(""); img.on('load', function(e)< console.log('Success!'); >).on('error', function(e) < console.log('ERROR!'); >); img.appendTo("body");   

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