不得不分享的JavaScript常用方法函数集（上）

本文中，收集了一些比较常用的Javascript函数，希望对学习JS的朋友们有所帮助。
1. 字符串长度截取

function cutstr(str, len) {
  var temp,
    icount = 0,
    patrn = /[^\x00-\xff]/，
    strre = "";
  for (var i = 0; i < str.length; i++) {
    if (icount < len - 1) {
      temp = str.substr(i, 1);
        if (patrn.exec(temp) == null) {
          icount = icount + 1
      } else {
        icount = icount + 2
      }
      strre += temp
      } else {
      break;
    }
  }
  return strre + "..."
}

2. 替换全部

String.prototype.replaceAll = function(s1, s2) {
  return this.replace(new RegExp(s1, "gm"), s2)
}

3. 清除空格

String.prototype.trim = function() {
  var reExtraSpace = /^\s*(.*?)\s+$/;
  return this.replace(reExtraSpace, "$1")
}

4. 清除左空格/右空格

function ltrim(s){ return s.replace( /^(\s*| *)/, ""); } 
function rtrim(s){ return s.replace( /(\s*| *)$/, ""); }

5. 判断是否以某个字符串开头

String.prototype.startWith = function (s) {
  return this.indexOf(s) == 0
}

6. 判断是否以某个字符串结束

String.prototype.endWith = function (s) {
  var d = this.length - s.length;
  return (d >= 0 && this.lastIndexOf(s) == d)
}

7. 转义html标签

function HtmlEncode(text) {
  return text.replace(/&/g, '&').replace(/\"/g, '"').replace(/</g, '<').replace(/>/g, '>')
}

8. 时间日期格式转换

Date.prototype.Format = function(formatStr) {
  var str = formatStr;
  var Week = ['日', '一', '二', '三', '四', '五', '六'];
  str = str.replace(/yyyy|YYYY/, this.getFullYear());
  str = str.replace(/yy|YY/, (this.getYear() % 100) > 9 ? (this.getYear() % 100).toString() : '0' + (this.getYear() % 100));
  str = str.replace(/MM/, (this.getMonth() + 1) > 9 ? (this.getMonth() + 1).toString() : '0' + (this.getMonth() + 1));
  str = str.replace(/M/g, (this.getMonth() + 1));
  str = str.replace(/w|W/g, Week[this.getDay()]);
  str = str.replace(/dd|DD/, this.getDate() > 9 ? this.getDate().toString() : '0' + this.getDate());
  str = str.replace(/d|D/g, this.getDate());
  str = str.replace(/hh|HH/, this.getHours() > 9 ? this.getHours().toString() : '0' + this.getHours());
  str = str.replace(/h|H/g, this.getHours());
  str = str.replace(/mm/, this.getMinutes() > 9 ? this.getMinutes().toString() : '0' + this.getMinutes());
  str = str.replace(/m/g, this.getMinutes());
  str = str.replace(/ss|SS/, this.getSeconds() > 9 ? this.getSeconds().toString() : '0' + this.getSeconds());
  str = str.replace(/s|S/g, this.getSeconds());
  return str
}

9. 判断是否为数字类型

function isDigit(value) {
  var patrn = /^[0-9]*$/;
  if (patrn.exec(value) == null || value == "") {
    return false
  } else {
    return true
  }
}

10. 设置cookie值

function setCookie(name, value, Hours) {
  var d = new Date();
  var offset = 8;
  var utc = d.getTime() + (d.getTimezoneOffset() * 60000);
  var nd = utc + (3600000 * offset);
  var exp = new Date(nd);
  exp.setTime(exp.getTime() + Hours * 60 * 60 * 1000);
  document.cookie = name + "=" + escape(value) + ";path=/;expires=" + exp.toGMTString() + ";domain=360doc.com;"
}

11. 获取cookie值

function getCookie(name) {
  var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
  if (arr != null) return unescape(arr[2]);
  return null
}

12. 加入收藏夹

function AddFavorite(sURL, sTitle) {
  try {
    window.external.addFavorite(sURL, sTitle)
  } catch(e) {
    try {
      window.sidebar.addPanel(sTitle, sURL, "")
    } catch(e) {
      alert("加入收藏失败，请使用Ctrl+D进行添加")
    }
  }
}

13. 设为首页

function setHomepage() {
  if (document.all) {
    document.body.style.behavior = 'url(#default#homepage)';
    document.body.setHomePage('http://w3cboy.com')
  } else if (window.sidebar) {
    if (window.netscape) {
      try {
        netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect")
      } catch(e) {
        alert("该操作被浏览器拒绝，如果想启用该功能，请在地址栏内输入 about:config,然后将项 signed.applets.codebase_principal_support 值该为true")
        }
    }
    var prefs = Components.classes['@mozilla.org/preferences-service;1'].getService(Components.interfaces.nsIPrefBranch);
    prefs.setCharPref('browser.startup.homepage', 'http://w3cboy.com')
  }
}

14. 加载样式文件

function LoadStyle(url) {
  try {
    document.createStyleSheet(url)
  } catch(e) {
    var cssLink = document.createElement('link');
    cssLink.rel = 'stylesheet';
    cssLink.type = 'text/css';
    cssLink.href = url;
    var head = document.getElementsByTagName('head')[0];
    head.appendChild(cssLink)
  }
}

15. 返回脚本内容

function evalscript(s) {
  if(s.indexOf('<script') == -1) return s;
  var p = /<script[^\>]*?>([^\x00]*?)<\/script>/ig;
  var arr = [];
  while(arr = p.exec(s)) {
    var p1 = /<script[^\>]*?src=\"([^\>]*?)\"[^\>]*?(reload=\"1\")?(?:charset=\"([\w\-]+?)\")?><\/script>/i;
    var arr1 = [];
    arr1 = p1.exec(arr[0]);
    if(arr1) {
      appendscript(arr1[1], '', arr1[2], arr1[3]);
    } else {
      p1 = /<script(.*?)>([^\x00]+?)<\/script>/i;
      arr1 = p1.exec(arr[0]);
      appendscript('', arr1[2], arr1[1].indexOf('reload=') != -1);
    }
  }
  return s;
}

16. 清除脚本内容

function stripscript(s) {
  return s.replace(/<script.*?>.*?<\/script>/ig, '');
}

17. 动态加载脚本文件

function appendscript(src, text, reload, charset) {
  var id = hash(src + text);
  if(!reload && in_array(id, evalscripts)) return;
  if(reload && $(id)) {
    $(id).parentNode.removeChild($(id));
  }
  evalscripts.push(id);
  var scriptNode = document.createElement("script");
  scriptNode.type = "text/javascript";
  scriptNode.id = id;
  scriptNode.charset = charset ? charset : (BROWSER.firefox ? document.characterSet : document.charset);
  try {
    if(src) {
      scriptNode.src = src;
      scriptNode.onloadDone = false;
      scriptNode.onload = function () {
        scriptNode.onloadDone = true;
        JSLOADED[src] = 1;
       };
       scriptNode.onreadystatechange = function () {
         if((scriptNode.readyState == 'loaded' || scriptNode.readyState == 'complete') && !scriptNode.onloadDone) {
          scriptNode.onloadDone = true;
          JSLOADED[src] = 1;
        }
       };
    } else if(text){
      scriptNode.text = text;
    }
    document.getElementsByTagName('head')[0].appendChild(scriptNode);
  } catch(e) {}
}

18. 返回按ID检索的元素对象

function $(id) {
  return !id ? null : document.getElementById(id);
}

19. 跨浏览器绑定事件

function addEventSamp(obj,evt,fn){ 
  if(!oTarget){return;}
  if (obj.addEventListener) { 
    obj.addEventListener(evt, fn, false); 
  }else if(obj.attachEvent){ 
    obj.attachEvent('on'+evt,fn); 
  }else{
    oTarget["on" + sEvtType] = fn;
  } 
}

20. 跨浏览器删除事件

function delEvt(obj,evt,fn){
  if(!obj){return;}
  if(obj.addEventListener){
    obj.addEventListener(evt,fn,false);
  }else if(oTarget.attachEvent){
    obj.attachEvent("on" + evt,fn);
  }else{
    obj["on" + evt] = fn;
  }
}

21. 为元素添加on方法

Element.prototype.on = Element.prototype.addEventListener;
 
NodeList.prototype.on = function (event, fn) {、
  []['forEach'].call(this, function (el) {
    el.on(event, fn);
  });
  return this;
};

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