常用JavaScript函数 1 - 15 （自我总结）

常用JavaScript函数 16 - 30（自我总结）

常用JavaScript函数 31- 46 （自我总结）

1、调整图片大小，不走形（FF IE 兼容）/ 剪切图片（overflow:hidden）

2、控制textarea区域文字数量

3、点击显示新窗口

4、 input框自动随内容自动变长

5、添加收藏夹

6、设置首页

7、 Jquery + Ajax 判断用户是否存在

8、判断email格式是否正确

9、综合判断用户名（长度，英文字段等）

10、新闻滚动

11、只允许输入正整数（shopping cart 使用）或者正数（正整数和正小数）

12、转换字符串为数字

13、判断文件格式（获得文件后缀）

14、截取字符串

15、分割字符串

1、调整图片大小，不走形（FF IE 兼容）

// 用法 <img src="this_image_path.jpg" οnlοad="DrawImage(this,450,450);" />function DrawImage(ImgD,FitWidth,FitHeight){var image=new Image();image.src=ImgD.src;if(image.width>0 && image.height>0){if(image.width/image.height>= FitWidth/FitHeight){if(image.width>FitWidth){ImgD.width=FitWidth;ImgD.height=(image.height*FitWidth)/image.width;}else{ImgD.width=image.width;ImgD.height=image.height;}} else{if(image.height>FitHeight){ImgD.height=FitHeight;ImgD.width=(image.width*FitHeight)/image.height;}else{ImgD.width=image.width;ImgD.height=image.height;}}}}

通过 overflow：hidden进行剪切：

function clipImage(o, w, h){ var img = new Image(); img.src = o.src; if(img.width >0 && img.height>0) { if(img.width/img.height >= w/h) { if(img.width > w) {            o.width = (img.width*h)/img.height; o.height = h; //o.setAttribute("style", "marginLeft:-" + ((o.width-w)/2).toString() + "px");$(o).css("margin-left", "-"+((o.width-w)/2).toString() + "px");} else { o.width = img.width; o.height = img.height; }            } else { if(img.height > h) { o.height = (img.height*w)/img.width; o.width = w; //o.setAttribute("style", "margin-top:-" + ((o.height-h)/2).toString() + "px");//$(o).css("style", "margin-top:-" + ((o.height-h)/2).toString() + "px");$(o).css("margin-top", "-"+((o.height-h)/2).toString() + "px");} else { o.width = img.width; o.height = img.height; }           } }
}

实例：

<style type="text/css">ul{list-style:none;}ul li{float:left;padding:1px;border:#ccc 1px solid;width:120px;height:120px;overflow:hidden;text-align:center;over-flow:hidden;}
</style>
<ul>  <li><img src="1.jpg" οnlοad="DrawImage(this,120,120);" /></li><li><img src="2.jpg" οnlοad="clipImage(this,120,120);" /></li>
</ul>

2、控制textarea区域文字数量

<script>
/*** Calculate how many characters remain in a textarea (jQuery)* @param string textarea* @param int maxLength* @param string div*/
function charsRemain(textarea, maxLength, div) {var currentLength = $(textarea).val().length;var charsLeft = maxLength - currentLength;if (charsLeft < 0) { charsLeft = 0; }$("#"+ div +"_charsRemain").html(charsLeft);if (currentLength > maxLength) {var fullText = $(textarea).val().substring(0, maxLength);$(textarea).val(fullText);}
}/*** Calculate how many characters remain in a textarea (javascript)* @param string textarea* @param int maxLength* @param string div*/
function charsRemain(textarea, maxLength, div) {var currentLength = textarea.value.length;var charsLeft = maxLength - currentLength;if (charsLeft < 0) { charsLeft = 0; }document.getElementById(div +"_charsRemain").innerHTML = charsLeft;if (currentLength > maxLength) {var fullText = textarea.value.substring(0, maxLength);textarea.value = fullText;}
}
</script><textarea rows="5" cols="15" οnkeyup="charsRemain(this, 250, 'textarea');"></textarea><span id="textarea_charsRemain">250</span> characters remaining

3、点击显示新窗口

//弹窗
function g_OpenWindow(pageURL, innerWidth, innerHeight)
{   var ScreenWidth = screen.availWidthvar ScreenHeight = screen.availHeightvar StartX = (ScreenWidth - innerWidth) / 2var StartY = (ScreenHeight - innerHeight) / 2var wins = window.open(pageURL, 'OpenWin', 'left='+ StartX + ', top='+ StartY + ', Width=' + innerWidth +', height=' + innerHeight + ', resizable=yes, scrollbars=yes, status=no, toolbar=no, menubar=no, location=no')wins.focus();
}

<script language="JavaScript">// 自动弹出窗口var whatsNew = open('','_blank','top=50,left=50,width=200,height=300,' + 'menubar=no,toolbar=no,directories=no,location=no,' + 'status=no,resizable=no,scrollbars=yes');whatsNew.document.write('<center><b>news</b>< /center>');whatsNew.document.write('<p>this is a test');whatsNew.document.write('<p>deos address');whatsNew.document.write('<p align="right">' + '<a href="javascript:self.close()">Close</a>');whatsNew.document.close();
</script>

不幸的是，很多浏览器会屏蔽弹出窗口，你需要手动允许后方可看到！下面是强制弹出窗口，原理就是创建一个form，通过post，打开，哈哈，原理很简单~

  <script language="javascript">  function ForceWindow (){  this.r = document.documentElement;  this.f = document.createElement("FORM");  this.f.target   =   "_blank";  this.f.method   =   "post";  this.r.insertBefore(this.f, this.r.childNodes[0]);  //XML DOM : insertBefore() 方法可在已有的子节点前插入一个新的子节点。 insertBefore(newchild,refchild)}   ForceWindow.prototype.pop = function (sUrl){  this.f.action = sUrl;  this.f.submit();  }  window.force  = new ForceWindow();  </script>  <body onLoad="window.force.pop('http://deographics.com/')">  <div>this is a test ! we will open the deographics's website~~</div></body>

当然还有更好的办法就是

<script>function openWin(){window.showModalDialog(url,window, "help:no;scroll:no;resizable:no;status:0;dialogWidth:420px;dialogHeight:200px;center:yes");}
</script>

更多请看：javascript基础入门

4、input框自动随内容自动变长

// input auto length// <input name="words" size="2" maxlength="100" οnkeyup="checkLength(this)"/><span id="char">0</span>function checkLength(which) {var maxchar=100;//var oTextCount = document.getElementById("char");  iCount = which.value.replace(/[^\u0000-\u00ff]/g,"aa").length;if(iCount<=maxchar){//oTextCount.innerHTML = "<font color=#FF0000>"+ iCount+"</font>";which.style.border = '1px dotted #FF0000';which.size=iCount+2;}else{alert('Please input letter less than '+ maxchar);}}