Chained Characters

chain_detect.js

var a = "efgaaa123";

var chain = 0;
var chains = [];
var prev = -1, prev2, current;
for(let i= 0; i < a.length; i++ ){
	current = a.charCodeAt(i);
  if( prev + 1 == current && prev2 + 1 == prev ){
  	chain ++;
		chains.push(String.fromCharCode.apply(null, [prev2, prev, current]))
  }
  
  prev2 = prev;
  prev = current;
}


console.log('chaing string', chain, chains)