JavaScript implements palindrome number, narcissus number judgment and output Fibonacci sequence

    //  judge if a number is a palindrome                   //  method One: First convert the number to a string, then the first and the last number, then the second and the penultimate number ... is equal to     function palindromenumber1 (num) {         var str = num.tostring ();         var flag  = true;        var len = str.length;         for (var i = 0; i <  (len -  1) ( / 2; i++) {            if (  str.charat (i)  != str.charat (len-i-1)  ) {                 flag = false;                 break;            }    &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;IF (flag) {             console.log (num +  "  is a palindrome number");         }else{             console.log (num +  "  not palindrome number");                     }    }     PalindromeNumber1 (123456321); // 123456321  is not a palindrome number              //  method Two: Another way of writing     function palindromenumber2 (num ) {        var str = num.tostring ();          Var flag = true;        var begin = 0,  end = str.length - 1;           while ( begin < end ) {             if (Str.charat (BEGIN)  == str.charat (end)) {                 begin ++;                 end --;             }else{                 flag = false;                 break;            }     &nbSP;&NBSP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;IF (flag) {             console.log (num +  "  is a palindrome number");         }else{             Console.log (num +  "  not palindrome number");                     }    }     PalindromeNumber2 (123456321); // 123456321  is not a palindrome number              //  method Three:  will judge the number inversion, and then determine whether the two numbers before and after the equality     function  Invertednumber (num) {         var nnum= 0;         while ( num != 0) {              nnum *= 10;            nnum =  nnum +  (nnum % 10);             num = math.floor ( num / 10 );          }        return nNum;    }     function palindromenumber3 (num) {        var  nnum = invertednumber (num);  //  a number in reverse order          if ( nnum == num) {                 //  determine if the inverse number is the same as the original number              console.log (num +  "  is a palindrome number");         } Else{    &nbsP;       console.log (num +  "  not palindrome number");          }    }    palindromenumber3 ( 123456321); // 123456321  not palindrome number                  //  judge whether a number is Narcissus number:  daffodil number refers to a  n  digit   ( n≥3 ), The sum of the numbers on each of its bits is equal to its own  n  power.         //   converts an array to a string, and then adds the number n power to each position, respectively      function narcissusnumber (num) {        var str =  num.tostring ();        var len = str.length;         var result = 0;         for (var i=0; i<len; i++) {          &Nbsp;  result += math.pow (Str.charat (i),  len);         }        if (Result == num) {             console.log (num +  "  is narcissus number");         }else{             console.log (num +  "  not daffodils");        }     }    narcissusnumber (153);                     //  Fibonacci sequence:  output before n number     /*         Fibonacci Series: 1, 1, 2, 3, 5, 8, 13, 21, 、......           function: Use formula F[n]=f[n-1]+f[n-2], recursive calculation, recursive end condition is f[1]=1,f[2]=1.     */        //  recursive:  the nth Fibonacci number   (  method one  )     function &NBSP;FB1 (n) {         if ( n==1 | | &NBSP;N==&NBSP;2) {            return 1;  &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;RETURN&NBSP;FB1 (n-1 ) &NBSP;+&NBSP;FB1 (n-2);    }    //  output First n Fibonacci number     &NBSP;FUNCTION&NBSP;FIBONACCI1 (num) {        console.log (1);         for (var i=2; i <= num; i++) {             console.log (FB1 (i));      &NBSP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;&NBSP;FIBONACCI1 (5);             //  non-recursive:  to find the nth Fibonacci number   (  method two  ) &NBSP;&NBSP;&NBSP;&NBSP;FUNCTION&NBSP;FB2 (n) {         var a =1, b =1, result=1;         for (var i =2; i<= n; i++) {             result = a + b;             a = b;             b = result;        }         return result;    }    //   Outputs the first n Fibonacci numbers     function fibonacci2 (num) {         console.log (1);         for (var i=1; i <  num; i++) {             console.log (FB2 (i));         }    }    fibonacci2 (5);            //  non-recursive: Find the nth Fibonacci number   (  method two  )     FUNCTION&NBSP;FB3 (n) {       var result = [1,1];        if ( n== 1 | |  n ==2) {            return 1;        }       for (var i = 2;  i < n; i++ ) {             result[i] = result[i-1] + result[i-2];       }        return result[n-1];  &nBSP;}    //  outputs the first n Fibonacci numbers    function fibonacci3 (num) {         console.log (1);         for (var i=1;  i <= num; i++) {             Console.log (FB3 (i));        }    }     fibonacci3 (5);

JavaScript implements palindrome number, narcissus number judgment and output Fibonacci sequence