Javascript determines whether to press the enter key and resolves the differences between browsers

 
<li class="item pin"> 
<span class="overlabel" style="display: block;"> Please enter the verification code </span> 
<input type="text" class="txt" id="checkNum" name="checkNum" maxlength="4" onkeydown="keyboardEvent(event);" /> 
<img src="${basePath}/randomImageCodeStyle" width="60" height="28" id="chkNum" 　 title=" Click reload the verification code " style="cursor: hand" /> 
</li> 

 
//Listen for the Enter key to automatically commit events
function keyboardEvent(event){ 
var keyCode=event.keyCode ? event.keyCode:event.which?event.which:event.charCode;//Resolve differences between browsers
if(keyCode==13){ 
submitForm(); 
} 
} 

JQuery drops the standard button attribute and USES which, which is a bit confusing.

Which was introduced by Firefox and not supported by IE. Which means to get the keyCode of the keyboard.
Which in jQuery can be either a keyboard key or a mouse key.