Determine Div's Background Image Dimensions in jQuery
Problem:
Acquiring the width and height of a div's background image using jQuery seems elusive. Conventional attempts like $('#myDiv').css('background-image').height(); yield the "not a function" error.
Solution:
Fortunately, an ingenious solution exists. By leveraging the power of creating a new Image object, one can ascertain image dimensions even if they are not explicitly defined within the CSS. Here's an updated version of the script:
var image_url = $('#something').css('background-image'),
image;
// Extract the URL without the url() or url("") wrapper
image_url = image_url.match(/^url\("?(.+?)"?\)$/);
// Proceed if the image URL was obtained
if (image_url[1]) {
image_url = image_url[1];
// Create a new Image object
image = new Image();
// Trigger an event when the image is loaded
// This ensures we get the actual image dimensions
$(image).load(function () {
alert('Width: ' + image.width + '\nHeight: ' + image.height);
});
image.src = image_url;
}
Improved Approach (2018):
A more comprehensive solution is presented below, providing enhanced functionality and error handling:
var getBackgroundImageSize = function(el) {
// Extract the image URL
var imageUrl = $(el).css('background-image').match(/^url\(["']?(.+?)["']?\)$/);
// Create a deferred object
var dfd = new $.Deferred();
// Handle existence of image URL
if (imageUrl) {
// Create a new Image object
var image = new Image();
// Resolve the deferred on load, reject on error
image.onload = dfd.resolve;
image.onerror = dfd.reject;
// Assign the image source
image.src = imageUrl[1];
} else {
// Image not available, reject
dfd.reject();
}
// Return the dimensions if the image loads
return dfd.then(function() {
// Return the dimensions as an object
return { width: this.width, height: this.height };
});
};
// Sample usage
getBackgroundImageSize(jQuery('#mydiv'))
.then(function(size) {
// Success - log the dimensions
console.log('Image size is: ', size);
})
.fail(function() {
// Error - log failure message
console.log('Failed to determine image size');
});The above is the detailed content of How to Determine a Div's Background Image Dimensions Using jQuery?. For more information, please follow other related articles on the PHP Chinese website!
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