分享原生JavaScript技巧大收集(91~100)

文章来源：jquery教程 - http://www.jq-school.com/Show.aspx?id=315

不知不觉就收集了100个实用的JavaScript代码片段，希望可以帮到支持JquerySchool网站的网友和jquery学堂所有群的成员们。

91、原生JavaScript实现窗体改变事件resize的操作（兼容所以的浏览器）

(function(){var fn = function(){var w = document.documentElement ? document.documentElement.clientWidth : document.body.clientWidth,r = 1255,b = Element.extend(document.body),classname = b.className;if(w < r){//当窗体的宽度小于1255的时候执行相应的操作}else{//当窗体的宽度大于1255的时候执行相应的操作}}if(window.addEventListener){window.addEventListener('resize', function(){ fn(); });}else if(window.attachEvent){window.attachEvent('onresize', function(){ fn(); });}fn();})();

92、原生JavaScript用正则清除空格分左右

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

93、原生JavaScript判断变量是否空值

/** * 判断变量是否空值 * undefined, null, '', false, 0, [], {} 均返回true，否则返回false */function empty(v){    switch (typeof v){        case 'undefined' : return true;        case 'string'    : if(trim(v).length == 0) return true; break;        case 'boolean'   : if(!v) return true; break;        case 'number'    : if(0 === v) return true; break;        case 'object'    :             if(null === v) return true;            if(undefined !== v.length && v.length==0) return true;            for(var k in v){return false;} return true;            break;    }    return false;}

94、原生JavaScript实现base64解码

function base64_decode(data){var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";var o1, o2, o3, h1, h2, h3, h4, bits, i = 0,ac = 0,dec = "",tmp_arr = [];if (!data) { return data; }data += '';do { h1 = b64.indexOf(data.charAt(i++));h2 = b64.indexOf(data.charAt(i++));h3 = b64.indexOf(data.charAt(i++));h4 = b64.indexOf(data.charAt(i++));bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;o1 = bits >> 16 & 0xff;o2 = bits >> 8 & 0xff;o3 = bits & 0xff;if (h3 == 64) {tmp_arr[ac++] = String.fromCharCode(o1);} else if (h4 == 64) {tmp_arr[ac++] = String.fromCharCode(o1, o2);} else {tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);}} while (i < data.length);dec = tmp_arr.join('');dec = utf8_decode(dec);return dec;}

95、原生JavaScript实现utf8解码

function utf8_decode(str_data){var tmp_arr = [],i = 0,ac = 0,c1 = 0,c2 = 0,c3 = 0;str_data += '';while (i < str_data.length) {c1 = str_data.charCodeAt(i);if (c1 < 128) {tmp_arr[ac++] = String.fromCharCode(c1);i++;} else if (c1 > 191 && c1 < 224) {       c2 = str_data.charCodeAt(i + 1);tmp_arr[ac++] = String.fromCharCode(((c1 & 31) << 6) | (c2 & 63));i += 2;} else {c2 = str_data.charCodeAt(i + 1);c3 = str_data.charCodeAt(i + 2);tmp_arr[ac++] = String.fromCharCode(((c1 & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));i += 3;}} return tmp_arr.join('');}

96、原生JavaScript获取窗体可见范围的宽与高

function getViewSize(){var de=document.documentElement;var db=document.body;var viewW=de.clientWidth==0 ?  db.clientWidth : de.clientWidth;var viewH=de.clientHeight==0 ?  db.clientHeight : de.clientHeight;return Array(viewW ,viewH);}

97、原生JavaScript判断IE版本号（既简洁、又向后兼容！）

var _IE = (function(){    var v = 3, div = document.createElement('div'), all = div.getElementsByTagName('i');    while (        div.innerHTML = '<!--[if gt IE ' + (++v) + ']><i></i><![endif]-->',        all[0]    );    return v > 4 ? v : false ;}());

98、原生JavaScript获取浏览器版本号

function browserVersion(types) {    var other = 1;    for (i in types) {        var v = types[i] ? types[i] : i;        if (USERAGENT.indexOf(v) != -1) {            var re = new RegExp(v + '(\\/|\\s|:)([\\d\\.]+)', 'ig');            var matches = re.exec(USERAGENT);            var ver = matches != null ? matches[2] : 0;            other = ver !== 0 && v != 'mozilla' ? 0 : other;        } else {            var ver = 0;        }        eval('BROWSER.' + i + '= ver');    }    BROWSER.other = other;}

99、原生JavaScript半角转换为全角函数

function ToDBC(str){  var result = '';  for(var i=0; i < str.length; i++){    code = str.charCodeAt(i);    if(code >= 33 && code <= 126){      result += String.fromCharCode(str.charCodeAt(i) + 65248);    }else if (code == 32){      result += String.fromCharCode(str.charCodeAt(i) + 12288 - 32);    }else{      result += str.charAt(i);    }  } return result;}

100、原生JavaScript全角转换为半角函数 

function ToCDB(str){  var result = '';  for(var i=0; i < str.length; i++){    code = str.charCodeAt(i);    if(code >= 65281 && code <= 65374){      result += String.fromCharCode(str.charCodeAt(i) - 65248);    }else if (code == 12288){      result += String.fromCharCode(str.charCodeAt(i) - 12288 + 32);    }else{      result += str.charAt(i);    }  } return result;}