Javascript 泛化多个对象的函数 (Raphael JS)

Question

我正在使用 Raphael JS 库，并尝试创建可应用于任何目标的悬停In 和悬停输出函数。

我认为问题是缺少引用传递的函数(我对 JavaScript 很陌生)。

创建一组路径并添加属性以查看它们后:

Services = rsr.set();

Services.push(
    rsr.path("M698.5,98.617V96.09c0.289,0.256,0.636,0.484,1.04,0.689    c0.403,0.203,0.829,0.375,1.276,0.516c0.445,0.143,0.896,0.25,1.347,0.326c0.45,0.078,0.867,0.113,1.251,0.113    c1.318,0,2.305-0.242,2.955-0.732s0.977-1.193,0.977-2.111c0-0.496-0.106-0.922-0.325-1.291c-0.217-0.365-0.517-0.699-0.898-1.002    c-0.383-0.301-0.836-0.592-1.359-0.865c-0.521-0.275-1.088-0.568-1.689-0.875c-0.64-0.32-1.235-0.648-1.788-0.982    c-0.555-0.33-1.033-0.697-1.442-1.098c-0.408-0.398-0.729-0.854-0.964-1.359c-0.235-0.504-0.351-1.1-0.351-1.781    c0-0.834,0.184-1.561,0.549-2.178c0.366-0.615,0.846-1.125,1.442-1.525c0.596-0.398,1.273-0.697,2.036-0.893    c0.761-0.197,1.537-0.295,2.328-0.295c1.804,0,3.119,0.219,3.943,0.65v2.412c-1.082-0.748-2.468-1.123-4.161-1.123    c-0.468,0-0.938,0.051-1.404,0.148c-0.469,0.098-0.885,0.258-1.251,0.479c-0.367,0.223-0.665,0.504-0.894,0.854    c-0.23,0.35-0.346,0.775-0.346,1.275c0,0.471,0.087,0.873,0.262,1.215c0.174,0.342,0.433,0.65,0.772,0.932    c0.341,0.281,0.754,0.555,1.244,0.818c0.488,0.264,1.052,0.555,1.69,0.865c0.653,0.324,1.275,0.666,1.862,1.021    c0.587,0.357,1.103,0.754,1.546,1.188c0.441,0.432,0.793,0.916,1.054,1.443c0.258,0.525,0.389,1.133,0.389,1.811    c0,0.904-0.178,1.666-0.53,2.293c-0.353,0.625-0.828,1.137-1.43,1.523c-0.599,0.393-1.291,0.676-2.074,0.852    s-1.608,0.264-2.477,0.264c-0.29,0-0.646-0.025-1.071-0.072c-0.427-0.049-0.859-0.117-1.303-0.203    c-0.443-0.09-0.862-0.201-1.258-0.332C699.055,98.926,698.737,98.777,698.5,98.617z"),
    rsr.path("M722.425,93.344h-9.229c0.033,1.457,0.425,2.58,1.175,3.371    c0.747,0.791,1.776,1.188,3.089,1.188c1.473,0,2.825-0.484,4.061-1.457v1.969c-1.148,0.832-2.669,1.25-4.558,1.25    c-1.847,0-3.299-0.596-4.354-1.781c-1.058-1.188-1.583-2.855-1.583-5.01c0-2.035,0.575-3.691,1.729-4.975    c1.152-1.279,2.584-1.922,4.295-1.922c1.712,0,3.035,0.555,3.972,1.66s1.404,2.643,1.404,4.607L722.425,93.344L722.425,93.344z     M720.279,91.57c-0.008-1.211-0.299-2.15-0.875-2.822c-0.574-0.672-1.372-1.01-2.394-1.01c-0.987,0-1.825,0.354-2.515,1.061    c-0.69,0.707-1.114,1.629-1.277,2.771H720.279L720.279,91.57z"))
    ).attr({
    fill: '#010101',
    stroke: '#000000',
    'stroke-width': 0
});

我通过附加以下内容来添加悬停进入和悬停退出事件:

.hover(
    function(){Services.animate({"fill": "#128A8F"}, 500), 
    function(){Services.animate({"fill": "#010101"}, 500));

这工作得很好。

但是，我将此效果应用于脚本中的许多路径，并通过悬停框应用它，因此我需要能够使悬停功能更具延展性。

我尝试使用下面的方法将悬停目标概括为传递的对象，但它不起作用，可能是因为 JavaScript 是按值传递的:

function menuHoverIn(target){
        target.animate({
            "fill": "#128A8F"
        }, 500);
    };

function menuHoverOut(target){
        target.animate({
            "fill": "#010101"
        }, 500)
    };

那么如何让上述函数按照我期望的那样在 JavaScript 中工作呢？我只想对传递的对象进行动画处理。

谢谢!

Answer 1

您的问题非常模糊，但我想我明白您的意思:您只是希望能够将可重用的悬停函数传递到元素或集合中。

在给出解决方案之前，我必须纠正你一点:JavaScript 不是一种按值传递的语言，至少不是一直如此。 JavaScript 通过引用传递引用类型(对象)，原子类型(字符串、数字、 bool 值)通过值传递(除非它们包装在关联的对象类型中)。

此外，在继续之前，我想提供一些关于编写更好的 SO 问题(更有可能得到回答)的建议。首先，尝试将问题归结为简单易懂的问题。在这种情况下，没有人关心(或想看到)你的长路径。您可以用圆圈替换它们，这样您的问题就会更容易阅读。其次，提供重现问题所需的所有信息。并不是每个人都会知道设置 Raphael 对象等所涉及的细节。最好提供 jsfiddle (对于像 Raphael 这样可能没有 CDN 的库来说，这可能会很棘手——但我能够在 CDN 上找到 Raphael 的副本)。尝试遵循 JavaScript 约定；这将减少试图回答您问题的人之间的困惑。在您的情况下，您将您的对象称为 Services ，这不仅对问题的读者来说是不透明的，而且 JavaScript 中的大写变量通常是为对象构造函数保留的。

好的，开始讨论解决方案:

如果你看documentation for hover ，你看到.hover()需要两个函数，然后是两个上下文对象。这意味着 JavaScript 正在使用 call 调用函数。或apply ，它设置函数的上下文(即 this 变量)，就像它们是方法调用一样。所以，你想要的是这样的:

var paper = Raphael( 0, 0, 200, 200 );  // create Raphael surface
// re-usable hover functions:
function menuHoverIn(){
    // note the use of 'this'; we are animating the 'this' object,
    // as if this were a method on an object.  JavaScript is very
    // flexible this way, and this method can (and will) be called
    // as if it were a method of the element you're trying to animate
    this.animate({'fill': '#128A8F'}, 500);
};
function menuHoverOut(){
    this.animate({'fill': '#010101'}, 500);
};

var set = paper.set();   // create Raphael set; renamed from "Services" in OP
    set.push( paper.circle( 50, 50, 25, 25 ) )    // put a circle in the set
    .attr({                          // set attributes of all elements in set
        fill: '#010101',
        stroke: '#000',
        'stroke-width': 0
    })
// provide .hover function for entire set; notice how we pass in set itself
// as the hover in and out context (which will become the 'this' value)
.hover( menuHoverIn, menuHoverOut, set, set );

事实证明，Raphael 默认将上下文设置为正在操作的对象，因此在这种情况下设置上下文实际上是不必要的。这就足够了:

.hover( menuHoverIn, menuHoverOut );

这是一个jsfiddle demonstrating this solution .