ESLImage - a custom element, that provides flexible ways to include images on web pages. Was originally developed as an alternative to
<picture> element, but with more features inside.
- Different rendering modes:
cover- renders the image via
safe-ratio- renders the image via
background-imageCSS property, but also sets height using
fit- renders the image using inner
origin- renders the image using inner
<img>element, sets width/height attributes using image's original size;
inner-svg- renders svg content inside (the content is loaded via XHR request).
- Lazy loading modes:
- none - image starts loading immediately;
- manual - starts loading image when a marker is provided manually;
- auto - image starts loading only if it's visible and is inside or close to browser viewport area (determined using Intersection Observer API).
ESLMediaQuery- special syntax that allows defining different sources for different media queries. Supports media-query shortcuts.
- Marker class. ESL Image can add a specific class on the specified parent element when the image is ready. ESL Image itself also has markers that indicate its state.
- Provides events on state change (also supports inline syntax, e.g.
- Attributes observing.
ESL Image uses 'img' role if the role is not explicitly provided. If the role is 'img' then
alt attribute is used as the
aria-label for the image. In case
alt is not provided then an empty value is used as a fallback.
data-alt is considered a legacy attribute and is used only when the image was connected to DOM without
data-src - src paths with query conditions. See ESLMediaQuery (watched value)
data-src-base - base src path for paths described in data-src (watched value)
alt - alt image text (watched value)
data-alt(Deprecated) - alt image text, not observable
mode - rendering mode. Default -
origin- save origin image size (use inner
imgtag for rendering);
fit- use inner
img, but do not force its width;
cover- do not set self width/height; use 100% w/h of the container (use
save-ratio- fill 100% of container width and set the self height according to image ratio (use
inner-svg- load an SVG content via XHR request and render it inside.
lazy (optional) - enable lazy loading:
auto- IntersectionObserver mode: image starts loading as soon as it becomes visible in visual area
manual- start loading when
lazy-triggeredmarker is set manually
refresh-on-update [boolean] (optional) - Always update the original image as soon as image source is changed
inner-image-class (optional) - class to mark and search the inner image, 'inner-image' by default
container-class (optional) - class that will be added to the container when the image is ready
container-class-state (optional) - image state in which the container will be marked with
container-class(can be 'ready', 'loaded' or 'error')
container-class-target (optional) - ESLTraversingQuery to find the target to add
container-classto ('::parent' by default).
NOTE: ESL Image supports
title attribute like any HTML element, no additional reflection for that attribute is needed - it will work correctly according to HTML5.* REC
- ready [boolean] - appears when the image is ready (either loaded or failed to load)
- loaded [boolean] - appears when the image is loaded for the first time
- error [boolean] - appears when current image failed to load
- triggerLoad - shortcut function for manual adding
- currentSrc - image URL that is currently in use
- ready - emits when the image is ready (either loaded or failed to load)
- load - emits when the image is loaded (also when the path is changed)
- error - emits when the current source failed to load.