onprogress
/ˈɒnˌprəʊɡrɛs/
noun … “an event handler for tracking incremental data transfer.”
onprogress is an event handler used to observe the ongoing progress of a long-running operation, most commonly data transfer over a network. Instead of waiting for completion or failure, it provides continuous feedback while bytes are still moving.
onresize
/ˈɒnˌriːsaɪz/
noun … “an event handler triggered when dimensions change.”
onresize is an event handler used in interactive computing environments to detect when the size of a rendering context changes. Most commonly, this refers to changes in the browser window or viewport, but the underlying idea applies to any system where layout depends on dynamic dimensions.
onerror
/ˈɒnˌɛrər/
noun … “an event handler for error conditions.”
onerror is an event handler used in web and programming environments to detect and respond to errors at runtime. It acts as a kind of early-warning system … when something fails, breaks, or refuses to load, onerror is where control flows next.
In the browser world, onerror most commonly appears in two related contexts: global JavaScript error handling and resource-loading errors. Both serve the same philosophical role … catching failures before they disappear into silence.