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@draeton
Last active January 1, 2023 03:30
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Check the existence of an image file at `url` by creating a temporary Image element.
// Example Use
(function () {
function success() {
console.log("success: ", this.src);
}
function failure() {
console.log("failure: ", this.src);
}
// this fails
checkImage("http://www.google.com/", success, failure);
// this succeeds
checkImage("http://www.google.com/intl/en_com/images/srpr/logo3w.png", success, failure);
})();
(function (window) {
// Stores past URLs that failed to load. Used for a quick lookup
// and because `onerror` is not triggered in some browsers
// if the response is cached.
var errors = {};
// Check the existence of an image file at `url` by creating a
// temporary Image element. The `success` callback is called
// if the image loads correctly or the image is already complete.
// The `failure` callback is called if the image fails to load
// or has failed to load in the past.
window.checkImage = function (url, success, failure) {
var img = new Image(), // the
loaded = false,
errored = false;
// Run only once, when `loaded` is false. If `success` is a
// function, it is called with `img` as the context.
img.onload = function () {
if (loaded) {
return;
}
loaded = true;
if (success && success.call) {
success.call(img);
}
};
// Run only once, when `errored` is false. If `failure` is a
// function, it is called with `img` as the context.
img.onerror = function () {
if (errored) {
return;
}
errors[url] = errored = true;
if (failure && failure.call) {
failure.call(img);
}
};
// If `url` is in the `errors` object, trigger the `onerror`
// callback.
if (errors[url]) {
img.onerror.call(img);
return;
}
// Set the img src to trigger loading
img.src = url;
// If the image is already complete (i.e. cached), trigger the
// `onload` callback.
if (img.complete) {
img.onload.call(img);
}
};
})(this);
@alanmilinovic
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Nice and simple solution!

If error occur, is it possible to get error message like error 404 (Not Found) or 401 (Authorization Required)?
I can read error in console log, but is it possible to display error on web page or store it in database for later use...

Thank you in advance.

@sfentress
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@Amilino: as far as I know, img.onerror doesn't provide you with useful information such as the response code from the server. To do that, I think you would need to do an AJAX request for the image. This would give you the complete response.

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