sequence - Sequential strings javascript -

i'm stuck on sequential string generation, last iteration of code below, trying return ac.

var charcode = 'abcdefghijklmnopqrstuvwxyz0123456789_'; var arr = []; var len = 1; var current = 0;  for(var = 0; < 40; i++) {     if(current == charcode.length) {         current = 0         len++     }     var tmpstr = ''     for(var l = 0; l < len; l++) {         tmpstr = tmpstr + charcode[current];     }     console.log(tmpstr)     current++ } 

however, produces cc.

sorry, somehow deleted intended output

a, b, c ... aa, ab, ac ... ba, bc, bb ... ∞ 

my current understanding suggests within l < len loop should check if len > 1 , if break out , loop current charcode[x] can't wrap head around breaking in , out grows.

you can this:

var charcode = 'abcdefghijklmnopqrstuvwxyz0123456789_'; var arr = []; var len = 0; var current = 0;  for(var = 0; < 40; i++) {   if(current == charcode.length) {      current = 0;      len++;   }    var tmpstr = (len===0) ? '' : charcode[len-1];    tmpstr = tmpstr + charcode[current];   current++;   console.log(tmpstr); } 

in brief, didn't need second loop, iteration instead (which achieved through charcode[len-1]).

js bin here.

update

if need continuos loop until end of charset, can use this:

this 1 introduces third variable (digits) iteration , choses .substr() instead of single character out of charset, everytime end of charset reached, digit added. variable called x sets limit. have tried 4000 , looks working.

var charcode = 'abcdefghijklmnopqrstuvwxyz0123456789_',     arr = [],     len = 0,     digits = 2,     current = 0,     tmpstr = '';  var x = 4000;  for(var i=0; i<x; i++) {     if(current === charcode.length) {         current = 0;         len++;         if(tmpstr.substr(0,1) === charcode.substr(-digits,1) || tmpstr === charcode.substr(-1) + '' + charcode.substr(-1)) {             len = 1;             digits++;         }        }       if(digits === charcode.length) {          console.log(charcode);          console.log(i + ' results found');          break;      }       tmpstr = (len===0) ? '' : charcode.substr([len-1], digits-1);       tmpstr += charcode[current];      current++;      console.log(tmpstr); } 

final js bin here.