关于如何更好的监听元素属性的变化(转)

我们都知道，jQuery有一个onchange的事件来判断类似input或者textarea标签值变化的事件。

jQuery中是通过比如keyup,blur,click等事件来监听值的变化，如果变化就触发change事件。

jQuery.event.special.change = {
        filters: {
            focusout: testChange,
 
            beforedeactivate: testChange,
 
            click: function( e ) {
                var elem = e.target, type = elem.type;
 
                if ( type === "radio" || type === "checkbox" || elem.nodeName.toLowerCase() === "select" ) {
                    testChange.call( this, e );
                }
            },
 
            // Change has to be called before submit
            // Keydown will be called before keypress, which is used in submit-event delegation
            keydown: function( e ) {
                var elem = e.target, type = elem.type;
 
                if ( (e.keyCode === 13 &amp;&amp; elem.nodeName.toLowerCase() !== "textarea") ||
                    (e.keyCode === 32 &amp;&amp; (type === "checkbox" || type === "radio")) ||
                    type === "select-multiple" ) {
                    testChange.call( this, e );
                }
            },
 
            // Beforeactivate happens also before the previous element is blurred
            // with this event you can't trigger a change event, but you can store
            // information
            beforeactivate: function( e ) {
                var elem = e.target;
                jQuery._data( elem, "_change_data", getVal(elem) );
            }
        },
 
        setup: function( data, namespaces ) {
            if ( this.type === "file" ) {
                return false;
            }
 
            for ( var type in changeFilters ) {
                jQuery.event.add( this, type + ".specialChange", changeFilters[type] );
            }
 
            return rformElems.test( this.nodeName );
        },
 
        teardown: function( namespaces ) {
            jQuery.event.remove( this, ".specialChange" );
 
            return rformElems.test( this.nodeName );
        }
    };

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