Number Runs

by Chase Wilson

JavaScript

extractRun = (runs) => {
	let previous, start = runs[0], end;
  
  for (i = 0; i < runs.length; i++) {
  	
    if (!previous) {
    	previous = runs[i];
      start = previous;
      continue;
    }
    
    if ( (previous + 1) == runs[i]) {
    	previous = runs[i]
      end = previous;
    }
    
  }
  
  return [end?`${start}:${end}`:start, i];
}



function stringifyNumberRuns ( arrOfNumbers ) {
	let [run, i] = extractRun(arrOfNumbers);
}

console.log( stringifyNumberRuns([1]) ) //=> '1'
console.log( stringifyNumberRuns([1, 3]) )//=> '1,3'
console.log( stringifyNumberRuns([1, 2]) )//=> '1:2'
console.log( stringifyNumberRuns([1, 2, 3]) )//=> '1:3'
console.log( stringifyNumberRuns([0, 2, 3, 4, 6, 7, 9]) )//=> '0,2:4,6:7,9'