Summary and arrangement of commonly used functions in javascript_javascript skills

This article summarizes some commonly used js functions, including data operations, character replacement operations, date and encryption and decryption operation functions, as well as some simple verification functions. It is convenient for everyone to refer to. I believe it will be helpful to everyone.

1.Judgement of arrays by typeof, constructor and instanceof

Copy code The code 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-calling

Copy code The code is as follows:

(function (a, b) {
console.log(a b);//30 self-calling
})(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 sss

4. Numerical Judgment

Copy code The code is as follows:

function isNumber(n){
Return !isNaN(parseFloat(n)) && isFinite(n);
}
console.log(isNumber('e345'));

5. Array judgment

Copy code The code is as follows:

function isArray(obj){
Return Object.prototype.toString.call(obj) === '[object Array]' ;
}
console.log(isArray(arr));

6. Understanding length

Copy code The code 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 and decryption

Copy code The code is as follows:

function base64encode(str){
    var out,i,len,base64EncodeChars="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 /";
    var c1,c2,c3;
    len=str.length;
    i=0;
    out="";
    while(i         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         /* c1 */
        do{
            c1=base64DecodeChars[str.charCodeAt(i )&0xff];
        }while(i         if(c1==-1) break;
        /* c2 */
        do{
            c2=base64DecodeChars[str.charCodeAt(i )&0xff];
        }while(i         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         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         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         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         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:

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 a value of 0 to 23. example.

Copy code The code is 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 "minutes" part of the date, with a value of 0 to 59. See the example above.
(5) getMonth function: returns the "month" part of the date, with a value of 0 to 11. Among them, 0 represents January, 2 represents March, ..., and 11 represents December. See previous example.
(6) getSeconds function: Returns the "seconds" part of the date, with a value of 0 to 59. See previous example.
(7) getTime function: returns the system time.

I hope this article will be helpful to everyone’s JavaScript programming design.