本文整理归纳了一些js常用函数，其中包括对数据操作，字符替换操作，日期及加解密操作函数，还有一些简单的验证函数。便于大家查阅参考。相信对大家会有所帮助。
1.typeof、constructor、instanceof对数组的判断
复制代码 代码如下:
var arr = [1,5,6,9,8,5,4];
//var arr = new Array(1,5,6,9,8,5,4);
console.log(typeof arr);//object
console.log(arr.constructor());//[]
console.log(arr instanceof Array);//true
2.函数自调用
复制代码 代码如下:
(function (a, b) {
console.log(a + b);//30 自调用
})(10, 20);3.去除两边空格
function trim (str) {
return str.replace(/^s+|s+$/g, '');
}
console.log(' woshi sss ');// woshi sss
console.log(trim(' woshi sss '));//woshi sss
4.数字判断
复制代码 代码如下:
function isNumber(n){
return !isNaN(parseFloat(n)) && isFinite(n);
}
console.log(isNumber('e345'));
5.数组判断
复制代码 代码如下:
function isArray(obj){
return Object.prototype.toString.call(obj) === '[object Array]' ;
}
console.log(isArray(arr));
6.length的理解
复制代码 代码如下:
var myArray = [12 , 222 , 1000 ];
myArray.length = 0; // myArray 会变成空数组[].----- length是可读可写的属性
7、base64_encode加密,解密
复制代码 代码如下:
function base64encode(str){
var out,i,len,base64EncodeChars="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var c1,c2,c3;
len=str.length;
i=0;
out="";
while(i<len){
c1=str.charCodeAt(i++)&0xff;
if(i==len){
out+=base64EncodeChars.charAt(c1>>2);
out+=base64EncodeChars.charAt((c1&0x3)<<4);
out+="==";
break;
}
c2=str.charCodeAt(i++);
if(i==len){
out+=base64EncodeChars.charAt(c1>>2);
out+=base64EncodeChars.charAt(((c1&0x3)<<4)|((c2&0xF0)>>4));
out+=base64EncodeChars.charAt((c2&0xF)<<2);
out+="=";
break;
}
c3=str.charCodeAt(i++);
out+=base64EncodeChars.charAt(c1>>2);
out+=base64EncodeChars.charAt(((c1&0x3)<<4)|((c2&0xF0)>>4));
out+=base64EncodeChars.charAt(((c2&0xF)<<2)|((c3&0xC0)>>6));
out+=base64EncodeChars.charAt(c3&0x3F);
}
return out;
}
function base64decode(str){
var c1,c2,c3,c4,base64DecodeChars=new Array(-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-1,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1);
var i,len,out;
len=str.length;
i=0;
out="";
while(i<len){
/* c1 */
do{
c1=base64DecodeChars[str.charCodeAt(i++)&0xff];
}while(i<len&&c1==-1);
if(c1==-1) break;
/* c2 */
do{
c2=base64DecodeChars[str.charCodeAt(i++)&0xff];
}while(i<len&&c2==-1);
if(c2==-1) break;
out+=String.fromCharCode((c1<<2)|((c2&0x30)>>4));
/* c3 */
do{
c3=str.charCodeAt(i++)&0xff;
if(c3==61) return out;
c3=base64DecodeChars[c3];
}while(i<len&&c3==-1);
if(c3==-1) break;
out+=String.fromCharCode(((c2&0XF)<<4)|((c3&0x3C)>>2));
/* c4 */
do{
c4=str.charCodeAt(i++)&0xff;
if(c4==61) return out;
c4=base64DecodeChars[c4];
}while(i<len&&c4==-1);
if(c4==-1) break;
out+=String.fromCharCode(((c3&0x03)<<6)|c4);
}
return out;
}
function utf16to8(str){
var out,i,len,c;
out="";
len=str.length;
for (i=0;i<len;i++){
c=str.charCodeAt(i);
if((c>=0x0001)&&(c<=0x007F)){
out+=str.charAt(i);
} else if(c>0x07FF){
out+=String.fromCharCode(0xE0|((c>>12)&0x0F));
out+=String.fromCharCode(0x80|((c>>6)&0x3F));
out+=String.fromCharCode(0x80|((c>>0)&0x3F));
} else {
out+=String.fromCharCode(0xC0|((c>>6)&0x1F));
out+=String.fromCharCode(0x80|((c>>0)&0x3F));
}
}
return out;
}
function utf8to16(str){
var out,i,len,c;
var char2,char3;
out="";
len=str.length;
i=0;
while(i<len){
c=str.charCodeAt(i++);
switch (c>>4){
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
// 0xxxxxxx
out+=str.charAt(i-1);
break;
case 12:
case 13:
// 110x xxxx 10xx xxxx
char2=str.charCodeAt(i++);
out+=String.fromCharCode(((c&0x1F)<<6)|(char2&0x3F));
break;
case 14:
// 1110 xxxx 10xx xxxx 10xx xxxx
char2=str.charCodeAt(i++);
char3=str.charCodeAt(i++);
out+=String.fromCharCode(((c&0x0F)<<12)|((char2&0x3F)<<6)|((char3&0x3F)<<0));
break;
}
}
return out;
}
8、日期时间
getDay函数：返回星期几，值为0～6，其中0表示星期日，1表示星期一，...，6表示星期六。例：
复制代码 代码如下: