javascript - 在 Javascript 行为不稳定的情况下在两个状态之间应用转换

Question

我很难理解为什么转换没有按预期运行。它应该应用“from”，然后将“transition”添加到“el”，然后它应该运行“to”，最后 onTransitionEnd 它应该运行“callback”(前面是一些清除代码的代码过渡属性)。

在 Webkit 浏览器中，它会正确转换 slideDown，但 slideUp 是即时的。在 Firefox 中反向是正确的。

呃？

JSFiddle:http://jsfiddle.net/enhTd/

var $ = function(query) {
                var a = [],
                    n = document.querySelectorAll(query),
                    l = n.length;

                for( var i = 0; i<l; i++){
                    a.push(n[i]);
                    }
                if(l>1) {return a;} else {return a[0];}

                },
    $id = function(query) { return document.getElementById(query);},
    getSupportedPropertyName = function(properties) {
        for (var i = 0; i < properties.length; i++) {
            if (typeof document.body.style[properties[i]] != "undefined") {
                return properties[i];
            }
        }
        return null;
    },
    vendorTransitions = ["transition", "msTransition", "webkitTransition", "MozTransition", "OTransition"],
    prefixedTransitionProperty = getSupportedPropertyName(vendorTransitions),
    transition = function(opts){

        opts.from && opts.from();

        if(prefixedTransitionProperty){
            var c = opts.callback || function() {},
                el = opts.el,
                cb = function(event){
                    var ev = event, callback = c;
                    ev.target.removeEventListener(prefixedTransitionProperty+"End", cb);
                    ev.target.style[prefixedTransitionProperty] = "none";
                    if(callback) {
                        callback(ev);
                        }
                    };

            el.style[prefixedTransitionProperty] = opts.transition || "";
            el.addEventListener(prefixedTransitionProperty+"End", cb);
        }

        opts.to && opts.to();

    },
    slideDown = function(el, t){
        var style = el.style,
            h, oh = el.offsetHeight,
            t = t || 1000;

        //Grab real height
        style.height = "";
        h = el.offsetHeight;

        transition({
            "el": el,
            transition: "height "+t+"ms ease",
            from: function() {
                style.height = oh+"px";
            },
            to: function(){
                style.overflow = "hidden";
                style.height = h+"px";
                },
            callback: function(event){
                event.target.style.height = "";
                }
            });


    },
    slideUp = function(el, t){
        var style = el.style,
            h = el.offsetHeight,
            t = t || 1000;

        transition({
            "el": el,
            transition: "height "+t+"ms ease",
            from: function() {
                style.height = h+"px";
                },
            to: function(){
                style.overflow = "hidden";
                style.height = "0";
                }
            });

    },
    slideToggle = function(el, t){
        var t = t || 1000;

        if(el.style.height=="0px"){
            slideDown(el, t);
        } else {
            slideUp(el, t);
        }
    };


slideUp($id("intro"));
$("a[href='#intro']").forEach(function(el){
    el.addEventListener("click", function(ev) { 
        ev.preventDefault();
        if(ev.target.classList.contains("hide")){
            slideUp($(ev.target.hash));
        } else {
            slideDown($(ev.target.hash));
        }
    });
});
$("li h3").forEach(function(el){
    el.addEventListener("click", function(ev) { 
        ev.preventDefault();
        slideToggle(ev.target.parentNode);
    });
});

Answer 1

在某些浏览器中，您不能只设置初始状态、设置最终状态并期望 CSS 转换起作用。

相反，必须先设置初始状态，然后渲染它，然后才能设置最终状态并期望过渡运行。使其呈现的最简单方法是返回到事件循环，然后在 setTimeout() 调用后进行任何进一步处理(如设置最终状态)。