如何提高此 jquery 动画代码的性能

Question

我编写了一些代码，当我将鼠标悬停在一个元素上时，会在其周围添加四个箭头并循环动画，以便它们前后移动。

这是为了直观地显示元素是可拖动的。我使用hoverIntent 插件仅在用户打算将鼠标悬停在元素上时绘制箭头。我也在使用 jQueryUI 进行元素定位。

将一个项目附加到文档然后对其进行动画处理是我以前从未做过的事情，我确信我的编码很糟糕，导致性能不太理想。

我怎样才能让这段代码表现得更好？

jQuery.fx.interval = 1;

// Add Hover arrows
$('.table-row.songnamecolumn').livequery(function($songRow) {
    var $songRow = $(this).closest('tr').children('td');
    var $appenditem = $(this);
    var $this = $(this);

    var loop = function loop(){
        $('#toparrow').animate({ top:'-=15px'},500).animate({ top:'+=15px'},100);
        $('#bottomarrow').animate({ top:'+=15px'},500).animate({ top:'-=15px'},100);
        $('#leftarrow').animate({ left:'-=15px'},500).animate({ left:'+=15px'},100);
        $('#rightarrow').animate({ left:'+=15px'},500).animate({ left:'-=15px'},100);
    }

    $(this).hoverIntent({
        sensitivity: 3, // How sensitive the hoverIntent should be
        interval: 200, // How often in milliseconds the onmouseover should be checked
        over: slidedrag, // Function to call when mouseover is called    
        timeout: 200, // How often in milliseconds the onmouseout should be checked
        out: slidedragback // Function to call when mouseout is called    
    }); 

    function slidedrag() {  
        $('<div id="toparrow"></div>'
        +'<div id="leftarrow"></div>'
        +'<div id="rightarrow"></div>'
        +'<div id="bottomarrow"></div>').appendTo($appenditem);

        $('#toparrow').position ({
            of: $this,
            my: 'center top',
            at: 'center top',
            offset: "0 -18"
        })

        $('#bottomarrow').position ({
            of: $(this),
            my: 'center bottom',
            at: 'center bottom',
            offset: "0 18"
        })

        $('#leftarrow').position ({
            of: $(this),
            my: 'left center',
            at: 'left center',
            offset: "-10 0"
        })

        $('#rightarrow').position ({
            of: $(this),
            my: 'right center',
            at: 'right center',
            offset: "10 0"
        })

        $('#toparrow, #bottomarrow, #leftarrow, #rightarrow').animate({opacity:'0.5'},600);
        setInterval(loop, 600);
    }

    function slidedragback() {
        clearInterval(loop);
        $('#toparrow, #bottomarrow, #leftarrow, #rightarrow').animate({opacity:'0'},600);
        $('#toparrow,#bottomarrow,#leftarrow,#rightarrow').remove();
    }
});

Answer 1

我看到您不止一次选择相同的元素。我建议您将它们存储为局部变量并调用该变量：

var arrow_top = $('#toparrow');

删除代码块中的空白：

out: slidedragback // Function to call when mouseout is called    
}); 



function slidedrag() {

最后，避免过度动画。