(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
复制代码 代码如下:
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
复制代码 代码如下:
/**
* 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
复制代码 代码如下:
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
复制代码 代码如下: