Pages in a Book (logic puzzle).js

const START = 1;
const LENGTH = 990;
const ONE_COUNTS = 261;

let cur_length = 0;
let cur_number = 0;
let one_occurences = 0;

// while (cur_length < LENGTH) {
while (one_occurences < ONE_COUNTS) {
  cur_number++;
  cur_length += String(cur_number).length;
  one_occurences += (String(cur_number).match(/1/g) || []).length;
}

console.log(cur_length);
console.log(cur_number);
console.log(one_occurences);