Javascript is often used to summarize functions
- 2020-03-30 04:12:19
- OfStack
This article summarizes some common js functions, including data operations, character replacement operations, date and decryption operations, and some simple validation functions. For your reference. I believe it will be helpful to you.
Typeof, constructor, instanceof array judgment
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);//true2. Function call itself
(function (a, b) {
console.log(a + b);//
})(10, 20);3. Remove Spaces on both sides
function trim (str) {
return str.replace(/^s+|s+$/g, '');
}
console.log(' woshi sss ');// woshi sss
console.log(trim(' woshi sss '));//woshi sssNumber judgment
function isNumber(n){
return !isNaN(parseFloat(n)) && isFinite(n);
}
console.log(isNumber('e345'));5. Array judgment
function isArray(obj){
return Object.prototype.toString.call(obj) === '[object Array]' ;
}
console.log(isArray(arr));6. The understanding of the length
var myArray = [12 , 222 , 1000 ];
myArray.length = 0; // myArray It's going to be an empty array [].----- length Is a readable, writable property 7. Base64_encode encryption and decryption
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){
do{
c1=base64DecodeChars[str.charCodeAt(i++)&0xff];
}while(i<len&&c1==-1);
if(c1==-1) break;
do{
c2=base64DecodeChars[str.charCodeAt(i++)&0xff];
}while(i<len&&c2==-1);
if(c2==-1) break;
out+=String.fromCharCode((c1<<2)|((c2&0x30)>>4));
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));
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. Date and time
GetDay function: returns the day of the week, with values ranging from 0 to 6, where 0 represents Sunday, 1 represents Monday,... Six is Saturday. Ex. :
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. Cases.
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 a value of 0 ~ 59. See above.
(5)getMonth function: returns the "month" part of the date, with values ranging from 0 to 11. Where 0 represents January, 2 represents march... 11 is the month of December. See the previous example.
(6)getSeconds function: returns the "seconds" part of the date, with values ranging from 0 to 59. See the previous example.
(7)getTime function: returns the system time.