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来自snipplr的10个最实用的javascript代码片段

作者:Ei Sabai
翻译:Terry li - GBin1.com
英文: 10 most useful Javascript snippets from snipplr

下面的代码片段来自snipplr,一个代码片段库。他们都是用纯javascript书写的,没有实用任何javascript类库,比如,jQuery,Mootools,或者Dojo。

1. Email验证 Source

function checkMail(email){
  var filter  = /^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$/;
  if (filter.test(email)) {
    return true;
  }
  return false;
}

2.多选框的选项开关 Source

<script type="text/javascript">

function toggle_checkboxes(id) {
    if (!document.getElementById){ return; }
    if (!document.getElementsByTagName){ return; }
    var inputs = document.getElementById(id).getElementsByTagName("input");
    for(var x=0; x < inputs.length; x++) {
        if (inputs[x].type == 'checkbox'){
            inputs[x].checked = !inputs[x].checked;
        }
    }
}

</script>

<div id="parent_box">

    <input type="checkbox" name="foo" value="1" /> 1<br/>
    <input type="checkbox" name="foo" value="2" checked="checked" /> 2<br/>
    <input type="checkbox" name="foo" value="3" checked="checked" /> 3<br/>

    <br/>
    <input type="button" value="Toggle checkboxes"
        onclick="toggle_checkboxes('parent_box')" />

</div>

3. 图片预加载 Source

var images = new Array();

function preloadImages(){
    for (i=0; i < preloadImages.arguments.length; i++){
         images[i] = new Image();
        images[i].src = preloadImages.arguments[i];
    }
}

preloadImages("logo.jpg", "main_bg.jpg", "body_bg.jpg", "header_bg.jpg");

4. javascript cookies设置 Source

/**
 * Sets a Cookie with the given name and value.
 *
 * name       Name of the cookie
 * value      Value of the cookie
 * [expires]  Expiration date of the cookie (default: end of current session)
 * [path]     Path where the cookie is valid (default: path of calling document)
 * [domain]   Domain where the cookie is valid
 *              (default: domain of calling document)
 * [secure]   Boolean value indicating if the cookie transmission requires a
 *              secure transmission
 */
function setCookie(name, value, expires, path, domain, secure) {
    document.cookie= name + "=" + escape(value) +
        ((expires) ? "; expires=" + expires.toGMTString() : "") +
        ((path) ? "; path=" + path : "") +
        ((domain) ? "; domain=" + domain : "") +
        ((secure) ? "; secure" : "");
}

/**
 * Gets the value of the specified cookie.
 *
 * name  Name of the desired cookie.
 *
 * Returns a string containing value of specified cookie,
 *   or null if cookie does not exist.
 */
function getCookie(name) {
    var dc = document.cookie;
    var prefix = name + "=";
    var begin = dc.indexOf("; " + prefix);
    if (begin == -1) {
        begin = dc.indexOf(prefix);
        if (begin != 0) return null;
    } else {
        begin += 2;
    }
    var end = document.cookie.indexOf(";", begin);
    if (end == -1) {
        end = dc.length;
    }
    return unescape(dc.substring(begin + prefix.length, end));
}

/**
 * Deletes the specified cookie.
 *
 * name      name of the cookie
 * [path]    path of the cookie (must be same as path used to create cookie)
 * [domain]  domain of the cookie (must be same as domain used to create cookie)
 */
function deleteCookie(name, path, domain) {
    if (getCookie(name)) {
        document.cookie = name + "=" +
            ((path) ? "; path=" + path : "") +
            ((domain) ? "; domain=" + domain : "") +
            "; expires=Thu, 01-Jan-70 00:00:01 GMT";
    }
}

5. 下拉框排序 Source

function sortList(id) {
  var obj = document.getElementById("id");
  var values = new Array();
  for(var i = 0; i < obj.options.length; i++) {
    values.push(obj.options[i].innerHTML + "--xx--" + obj.options[i].value);
  }

  values = values.sort();

  for(var i = 0; i < values.length; i++) {
    valueArray = values[i].split('--xx--');
    obj.options[i].innerHTML = valueArray[0];
    obj.options[i].value = valueArray[1];
  }
}

6. 检测浏览器是否支持HTML5 video Source

// Check if the browser understands the video element.
function understands_video() {
  return !!document.createElement('video').canPlayType; // boolean
}

if ( !understands_video() ) {
  // Must be older browser or IE.
  // Maybe do something like hide custom
  // HTML5 controls. Or whatever...
  videoControls.style.display = 'none';
}

7. 得到浏览器的viewport宽度和高度 Source

<script type="text/javascript">
<!--

 var viewportwidth;
 var viewportheight;

 // the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight

 if (typeof window.innerWidth != 'undefined')
 {
      viewportwidth = window.innerWidth,
      viewportheight = window.innerHeight
 }

// IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)

 else if (typeof document.documentElement != 'undefined'
     && typeof document.documentElement.clientWidth !=
     'undefined' && document.documentElement.clientWidth != 0)
 {
       viewportwidth = document.documentElement.clientWidth,
       viewportheight = document.documentElement.clientHeight
 }

 // older versions of IE

 else
 {
       viewportwidth = document.getElementsByTagName('body')[0].clientWidth,
       viewportheight = document.getElementsByTagName('body')[0].clientHeight
 }
document.write('<p>Your viewport width is '+viewportwidth+'x'+viewportheight+'</p>');
//-->
</script>

8. 由class名字取得对象元素 Source

/*
    Written by Jonathan Snook, http://www.snook.ca/jonathan
    Add-ons by Robert Nyman, http://www.robertnyman.com
*/

function getElementsByClassName(oElm, strTagName, strClassName){
    var arrElements = (strTagName == "*" && document.all)? document.all : oElm.getElementsByTagName(strTagName);
    var arrReturnElements = new Array();
    strClassName = strClassName.replace(/-/g, "-");
    var oRegExp = new RegExp("(^|s)" + strClassName + "(s|$)");
    var oElement;
    for(var i=0; i<arrElements.length; i++){
        oElement = arrElements[i];
        if(oRegExp.test(oElement.className)){
            arrReturnElements.push(oElement);
        }
    }
    return (arrReturnElements)
}

9. 重定向延迟 Source

setTimeout( "window.location.href="http://walkerwines.com.au/'", 5*1000 );

10. iphone类型的方向变化效果 Source

window.addEventListener('load', setOrientation, false);
window.addEventListener('orientationchange', setOrientation, false);

function setOrientation() {
 var orient = Math.abs(window.orientation) === 90 ? 'landscape' : 'portrait';
 var cl = document.body.className;
 cl = cl.replace(/portrait|landscape/, orient);
 document.body.className = cl;
}

原文出处:来自snipplr的10个最实用的javascript代码片段

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