This article summarizes some commonly used functions for JS, including data operations, character replacement operations, date and encryption and decryption operations functions, as well as some simple verification functions. It is easy for everyone to consult and refer to. I believe it will be helpful to everyone.
1. Typeof, constructor, instanceof judgement on array
The code copy is as follows: 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. Function self-call
Copy the code as follows:(function (a, b) {
console.log(a + b);//30 Self-call
})(10, 20);3. Remove spaces on both sides
function trim (str) {
return str.replace(/^s+|s+$/g, '');
}
console.log(' woshi sss ');// woshi ss
console.log(trim(' woshi sss '));//woshi ss
4. Digital judgment
Copy the code as follows: function isNumber(n){
return !isNaN(parseFloat(n)) && isFinite(n);
}
console.log(isNumber('e345'));
5. Array judgment
Copy the code as follows: function isArray(obj){
return Object.prototype.toString.call(obj) === '[object Array]' ;
}
console.log(isArray(arr));
6. Length's understanding
The code copy is as follows: var myArray = [12 , 222 , 1000 ];
myArray.length = 0; // myArray will become an empty array[].----- length is a readable and writable property
7. Base64_encode encryption, decryption
Copy the code as follows: 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,-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);
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:
// 0xxxxxxxx
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. Date and time
getDay function: Returns the day of the week, the value is 0~6, where 0 represents Sunday, 1 represents Monday, ..., 6 represents Saturday. example:
Copy the code as follows: function DateDemo()
{
var d, day, x, s = "Today is: ";
var x = new Array("Sunday", "Monday", "Tuesday");
var x = x.concat("Wednesday","Thursday", "Friday");
var x = x.concat("Saturday");
d = new Date();
day = d.getDay();
return(s += x[day]);
}
(3) getHouse function: Returns the "hour" part of the date, with values ranging from 0 to 23. example.
Copy the code as follows: function TimeDemo()
{
var d, s = "The current local time is: ";
var c = ":";
d = new Date();
s += d.getHours() + c;
s += d.getMinutes() + c;
s += d.getSeconds() + c;
s += d.getMilliseconds();
return(s);
}
(4) getMinutes function: Returns the "minute" part of the date, with values ranging from 0 to 59. See the above example.
(5) getMonth function: Returns the "month" part of the date, with values ranging from 0 to 11. Where 0 means January, 2 means March,..., 11 means December. See the previous example.
(6) getSeconds function: Returns the "second" part of the date, with values ranging from 0 to 59. See the previous example.
(7) getTime function: Returns the system time.
I hope this article will be helpful to everyone's JavaScript programming.