


The example in this article describes how jQuery simulates the free fall motion of objects. Share it with everyone for your reference, the details are as follows:
The screenshot of the running effect is as follows:
Click here to view the online demonstration.
Click here for the complete example codeDownload from this site.
The specific code is as follows:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>自由落体</title> <script src="jquery-1.7.1.min.js" type="text/javascript"></script> <script type="text/javascript" > $(document).ready(function () { }); var all_Height = 500; var a = 9.8; // 加速度 var v = 0; var prev_Time = 0; var prev_Speed = 0; var prev_Height = 0; var speed = 0; // 获取当前的高度 var getHeight = function (obj) { return obj.offset().top; } // 获取当前的速度 var getSpeed = function (time, a) { return time * a; } // 向下走时获得当前物体所走的路径 var getCurrentHeight = function (time) { return 1 / 2 * a * time * time; } // 向上走时获得当前物体所走的路径 var getCurrentHeight2 = function (speed, time) { return speed * time - 1 / 2 * a * time * time; } // 向下跑 function down() { prev_Time = 0; var interval = setInterval(function () { if (getHeight($(".obj")) < all_Height) { prev_Time = prev_Time + 0.1; var height = getCurrentHeight(prev_Time) + prev_Height; $(".obj").css("top", height + "px"); $(".info").append("<div>" + height + "</div>"); } else { speed = getSpeed(a, prev_Time); prev_Speed = speed; clearInterval(interval); up(); } }, 5); } // 向上跑 function up() { prev_Time = 0; prev_Speed -= 4; // 动能损耗 var interval = setInterval(function () { if (speed > 0) { speed = prev_Speed - getSpeed(a, prev_Time); prev_Time = prev_Time + 0.1; var height = all_Height - getCurrentHeight2(prev_Speed, prev_Time); $(".obj").css("top", height + "px"); } else { clearInterval(interval); prev_Height = $(".obj").offset().top; if (prev_Height < all_Height) { down(); } } }, 5); } function play() { alert('play'); down(); document.getElementById("obj").onclick = null; } </script> <style type="text/css"> body{ margin:0 0 0 0 ; background:#FFFFFF;} .title { text-align:center; color:#666666; border-bottom:2px solid gray; font-size:30px; line-height:100px; font-weight:bolder;} .obj { background-image:url('a.jpg'); width:50px; height:50px; position:absolute; top:0; left:0; } </style> </head> <body> <div style="height:550px; border-bottom:2px solid gray;"> <div class="title" >自由落体大模拟<span style="font-size:12px;">(点击图片让它落下)</span></div> </div> <div class="obj" id="obj" onclick="play();" ></div> </body> </html>
Readers who are interested in more content related to js sports can check out the special topic of this site: "Summary of JavaScript sports effects and techniques"
I hope this article will be helpful to everyone in jQuery programming.

实现方法:1、用“$("img").delay(毫秒数).fadeOut()”语句,delay()设置延迟秒数;2、用“setTimeout(function(){ $("img").hide(); },毫秒值);”语句,通过定时器来延迟。

区别:1、axios是一个异步请求框架,用于封装底层的XMLHttpRequest,而jquery是一个JavaScript库,只是顺便封装了dom操作;2、axios是基于承诺对象的,可以用承诺对象中的方法,而jquery不基于承诺对象。

修改方法:1、用css()设置新样式,语法“$(元素).css("min-height","新值")”;2、用attr(),通过设置style属性来添加新样式,语法“$(元素).attr("style","min-height:新值")”。

增加元素的方法:1、用append(),语法“$("body").append(新元素)”,可向body内部的末尾处增加元素;2、用prepend(),语法“$("body").prepend(新元素)”,可向body内部的开始处增加元素。

删除方法:1、用empty(),语法“$("div").empty();”,可删除所有子节点和内容;2、用children()和remove(),语法“$("div").children().remove();”,只删除子元素,不删除内容。

在jquery中,apply()方法用于改变this指向,使用另一个对象替换当前对象,是应用某一对象的一个方法,语法为“apply(thisobj,[argarray])”;参数argarray表示的是以数组的形式进行传递。

on()方法有4个参数:1、第一个参数不可省略,规定要从被选元素添加的一个或多个事件或命名空间;2、第二个参数可省略,规定元素的事件处理程序;3、第三个参数可省略,规定传递到函数的额外数据;4、第四个参数可省略,规定当事件发生时运行的函数。

去掉方法:1、用“$(selector).removeAttr("readonly")”语句删除readonly属性;2、用“$(selector).attr("readonly",false)”将readonly属性的值设置为false。


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