To help you better understand how you can use the step function [as posted by gdoron]
I created an example using the step function to get the remaining time:

(click the get state!thton to end the animation and rec themain time!)

demo with distance
demo with opacity

远距离学习 j 质量:

var time = 4000;
var distance = 300;
var currentTime = 0;

$( #ball ).animate({
    left: distance
}, {
    duration: time,
    step: function (now, fx) {

        currentTime = Math.round((now * time) / distance);
        var data = fx.prop +     + Math.round(now) +  ; <b>  + currentTime +  ms</b>  ;

        $( body ).append( <p>  + data +  </p> );
    },
    easing:  linear 
});

$( #getTime ).click(function () {
    $( #ball ).stop();
    $( body ).prepend( <p>currentTime is:  + currentTime +   ms; REMAINING:   + (time - currentTime) +  ms</p> );
});

• You can see how I used the fx.prop inside the animation step to get the (left) property that is currently animated.
  
• You can see how: knowing the animation time and the distance (opacity, whatever...) we can easily retrieve the stopped/paused state by some simple math ((now*time)/distance) and thanks to the returned now value.

我不知道为什么需要,但<条码>步骤<>/代码>。 帮助您获取这一价值:

<>功能>

第2版的囚犯(a)提供了一种步骤选择,即向 each升的每一步发射击退功能。 这一职能有助于使习惯的估算类型成为可能,或改变正在发生的估算。 它接受两个论点(现在和fx),这属于正在消化的多功能元素。

now: the numeric value of the property being animated at each step
fx: a reference to the jQuery.fx prototype object, which contains a number of properties such as elem for the animated element, start and end for the first and last value of the animated property, respectively, and prop for the property being animated.

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名单永远不会忘记<条码>步骤<>。 我曾经需要你做些什么,并写过我自己的话,简单地把它倒掉了剩下的时间,看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看一看(你一把这个数字 j倒就知道了)和“<>引人<>目前和目标不透明”。 然后,这种引人与总估算时间相乘,总金额从总时间中减去。 简单。

www.un.org/spanish/ecosoc Pseudo-code:

func calculate-time-left-in-a-running-fade-in-animation:
{
    var current_opacity = $elem.css( opacity );
    var target_opacity = this.getTargetOpacity();

    var total = this.getTotalAnimationTime();

    var quotient = current_opacity / target_opacity;
    return total - quotient * total;
}