下面是我的 Javascript 文件。雪在开始时看起来都很好，但是当它们中的一些到达屏幕底部时，就会发生某种奇怪的行为。雪开始出现意外行为，并以非编程方式反复上下移动。
我无法通过说明我的代码来弄清楚为什么。谁能给我一个关于我哪里出错的指针？
提前致谢！
/*
1. mimic the snow falling
*/
$(document).ready(function(){
// get the height and width of the browser window
var windowHeight = $(window).height();
var windowWidth = $(window).width();
// set the height and width of the #snowingScreen div equivalent to that of the window's
$('#snowingScreen').css('height', windowHeight);
$('#snowingScreen').css('width', windowWidth);
// this function is to generate snow randomly scattered around screen
function generateSnow() {
// generate snow using a for loop
for(i=0; i<4; i++){
// randomize the top position of the snow
var snowTop = Math.floor(Math.random()* (windowHeight/2) );
// randomize the left position of the snow
var snowLeft = Math.floor(Math.random()* (windowWidth - 10) );
// appending the snow to the #snowingScreen
$('#snowingScreen').append(
// generate the div representing the snow and setting properties using various jQuery methods
$('<div />')
.addClass('snow')
.css('top', snowTop)
.css('left', snowLeft)
.text('*')
);
}
// repeat the generateSnow() function for each 3 seconds
window.setTimeout(generateSnow, 3000);
}
// this function is to alter the position of each snow, using the handy .each() jQuery method
function snowFalling(){
// move the snow
$('.snow').each(function(key, value){
// check if the snow has reached the bottom of the screen
if( parseInt($(this).css('top')) > windowHeight - 80 ) {
// remove the snow from the HTML DOM structure
$(this).remove();
}
// set up a random speed
var fallingSpeed = Math.floor(Math.random() * 5 + 1);
// set up a random direction for the snow to move
var movingDirection = Math.floor(Math.random()*2);
// get the snow's current top
var currentTop = parseInt($(this).css('top'));
// get the snow's current top
var currentLeft = parseInt($(this).css('left'));
// set the snow's new top
$(this).css('top', currentTop + fallingSpeed );
// check if the snow should move to left or move to right
if( movingDirection === 0){
// set the snow move to right
$(this).css('left', currentLeft + fallingSpeed );
}else {
// set the snow move to left
$(this).css('left', currentLeft + -(fallingSpeed) );
}
});
// repeat the rollIt() function for each 200 microseconds
window.setTimeout(snowFalling, 200);
}
// call the function when the document is loaded completely
generateSnow();
snowFalling();
});
jsfiddle：http: //jsfiddle.net/dennisboys/8BNbh/2/embedded/result/