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javascript - Intercepting all key presses with jQuery before they are processed

问题描述:

I have a web page and I need to intercept all keypresses before they get dispatched to whatever element in the dom has the focus. When the user types something like ~goto:/index.html: (which in fact will come from a barcode scanner) I need to capture the key presses after the ~ to parse them once I get to the second :. I've managed to get something with the $(document).keypress() as follows:

$(document).ready(function() {

$(document).keypress(function(e) {

// do the processing here and

// return false when ignoring keystrokes

});

});

The problem is that I get the keypress after it has gone to the focussed element. Anyway to get it before so that I can in fact reject it?

网友答案:

You will probably have better luck with keydown it should fire before the event

also do this

$(document).keydown(function(e) {
    e.preventDefault();
});

calling preventDefault will stop normal process of the key press. Actually, you may be able to stay with keypress and just use the preventDefault to finish your interception needs.

网友答案:

read this about event bubbling. http://www.quirksmode.org/js/events_order.html

this works for firefox:

 document.addEventListener('keypress',function(e){alert('body1'); e.cancelBubble  = true;},true)

I'm not sure what will work for i.e. as the document i linked to says in i.e. the event bubbles from inwards upwards. you may have to try a different way round this. e.g. you could add an event handler to all the element that you do not want them handling the event and then prevent them handling the event in that event handler.

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