window.onerror事件用来自定义错误处理
Event reference: https://developer.mozilla.org/en-US/docs/Web/Events
http://w3c.github.io/html/webappapis.html#events
原文: https://developer.mozilla.org/en-US/docs/Web/API/GlobalEventHandlers/onerror
An event handler for the error
event. Error events are fired at various targets for different kinds of errors:
- When a JavaScript runtime error (including syntax errors and exceptions thrown within handlers) occurs, an
error
event using interfaceErrorEvent
is fired atwindow
andwindow.onerror()
is invoked (as well as handlers attached bywindow.addEventListener
(not only capturing)). - When a resource (such as an
<img>
or<script>
) fails to load, anerror
event using interfaceEvent
is fired at the element that initiated the load, and theonerror()
handler on the element is invoked. These error events do not bubble up to window, but (at least in Firefox) can be handled with a single capturingwindow.addEventListener
.
Installing a global error
event handler is useful for automated collection of error reports.
Syntax
For historical reasons, different arguments are passed to window.onerror
and element.onerror
handlers (as well as on error-type window.addEventListener
handlers).
window.onerror
window.onerror = function(message, source, lineno, colno, error) { ... }
Function parameters:
message
: error message (string). Available asevent
(sic!) in HTMLonerror=""
handler.source
: URL of the script where the error was raised (string)lineno
: Line number where error was raised (number)colno
: Column number for the line where the error occurred (number)error
: Error Object (object)
When the function returns true
, this prevents the firing of the default event handler.
window.addEventListener('error')
window.addEventListener('error', function(event) { ... })
event
of type ErrorEvent
contains all the information about the event and the error.