Question

我将以keydown事件监听器为例。

可以使用

$('#my-input').keydown(function(){
  //actions goes here
});

我知道上面的事件监听器在遇到keydown事件时会运行。

我需要像这样的“afterkeydown事件”：

$('#my-input').afterkeydown(function(){
  //actions after keydown listener has occured
});

但是我不想使用keyup事件监听器或任何类型的计时器来实现这一点因为当重复保持键并且定时器很慢时，键盘事件侦听器不会触发。

在这些限制下，keydown上的“回调事件监听器”是否可能，如果是这样，是否可以推广到所有Jquery事件监听器？意思是，是否有可能为Jquery创建'afterclick'，'afterdrop'，'afterclick'，...事件监听器？

Answer 1

因为听起来你真正想要做的就是在textarea被更改时随时得到通知，这里是我用于该特定问题的一些代码。只要通过键盘，拖放，鼠标等更改内容，它就会调用您的回调...

(function($) {

    var isIE = false;
    // conditional compilation which tells us if this is IE
    /*@cc_on
    isIE = true;
    @*/

    // Events to monitor if 'input' event is not supported
    // The boolean value is whether we have to 
    // re-check after the event with a setTimeout()
    var events = [
        "keyup", false,
        "blur", false,
        "focus", false,
        "drop", true,
        "change", false,
        "input", false,
        "textInput", false,
        "paste", true,
        "cut", true,
        "copy", true,
        "contextmenu", true
    ];
    // Test if the input event is supported
    // It's too buggy in IE so we never rely on it in IE
    if (!isIE) {
        var el = document.createElement("input");
        var gotInput = ("oninput" in el);
        if  (!gotInput) {
            el.setAttribute("oninput", 'return;');
            gotInput = typeof el["oninput"] == 'function';
        }
        el = null;
        // if 'input' event is supported, then use a smaller
        // set of events
        if (gotInput) {
            events = [
                "input", false,
                "textInput", false
            ];
        }
    }

    $.fn.userChange = function(fn, data) {
        function checkNotify(e, delay) {
            var self = this;
            var this$ = $(this);

            if (this.value !== this$.data("priorValue")) {
                this$.data("priorValue", this.value);
                fn.call(this, e, data);
            } else if (delay) {
                // The actual data change happens aftersome events
                // so we queue a check for after
                // We need a copy of e for setTimeout() because the real e
                // may be overwritten before the setTimeout() fires
                var eCopy = $.extend({}, e);
                setTimeout(function() {checkNotify.call(self, eCopy, false)}, 1);
            }
        }

        // hook up event handlers for each item in this jQuery object
        // and remember initial value
        this.each(function() {
            var this$ = $(this).data("priorValue", this.value);
            for (var i = 0; i < events.length; i+=2) {
                (function(i) {
                    this$.on(events[i], function(e) {
                        checkNotify.call(this, e, events[i+1]);
                    });
                })(i);
            }
        });
    }
})(jQuery);

用法是：

 $("#whatever").userChange(yourCallbackFn, optionalData);

预防事件监听器

1 个答案: