Javascript Reserved Keywords
Javascript Reserved Keywords
In JavaScript, reserved keywords are predefined words that have a special meaning in the language syntax. They cannot be used as identifiers (e.g., variable names, function names). These keywords fall into several categories:
| Category | Keywords |
|---|---|
| Language Features | break, case, catch, class, const, continue, debugger, default, delete, do, else, enum, export, extends, finally, for, function, if, import, in, instanceof, let, new, return, super, switch, this, throw, try, typeof, var, void, while, with, yield |
| Future Use | implements, interface, package, private, protected, public, static |
| Literals | null, true, false |
| Strict Mode Reserved | arguments, eval |
| Modules | await (used with async functions) |
List of Event Handlers
event handler names (like onclick, onload, etc.) should not be used as variable names in JavaScript because they are associated with DOM event handling in HTML. Here's a list of common event handlers in JavaScript:
| Event Category | Event Handlers |
|---|---|
| Mouse Events | onclick, ondblclick, onmousedown, onmouseup, onmouseover, onmousemove, onmouseout, onmouseenter, onmouseleave |
| Keyboard Events | onkeydown, onkeypress, onkeyup |
| Form Events | onblur, onchange, onfocus, oninput, oninvalid, onreset, onsearch, onselect, onsubmit |
| Window/Document Events | onabort, onafterprint, onbeforeprint, onbeforeunload, onerror, onhashchange, onload, onmessage, onoffline, ononline, onpagehide, onpageshow, onpopstate, onresize, onscroll, onstorage, onunload |
| Drag and Drop Events | ondrag, ondragend, ondragenter, ondragleave, ondragover, ondragstart, ondrop |
| Clipboard Events | oncopy, oncut, onpaste |
| Media Events | oncanplay, oncanplaythrough, oncuechange, ondurationchange, onemptied, onended, onloadeddata, onloadedmetadata, onloadstart, onpause, onplay, onplaying, onprogress, onratechange, onseeked, onseeking, onstalled, onsuspend, ontimeupdate, onvolumechange, onwaiting |
| Touch Events | ontouchcancel, ontouchend, ontouchmove, ontouchstart |
| Miscellaneous Events | onwheel, oncontextmenu, onanimationstart, onanimationend, onanimationiteration, ontransitionend |
Usage Note:
- Avoid using these keywords as variable, function, or identifier names.
- Some keywords (e.g., enum, implements) may not be fully implemented in JavaScript but are reserved for future use.