textpand.js

// todo: use https://github.com/transitive-bullshit/random

function rnorm() {
  return (
    Math.sqrt(-2 * Math.log(1 - Math.random())) *
    Math.cos(2 * Math.PI * Math.random())
  );
}

function textpand(text, length = text.length, sd = 0) {
  return [...new Array(length)]
    .map(
      (_, i) =>
        text[
          Math.min(
            Math.max(Math.floor((text.length * i) / length + rnorm() * sd), 0),
            text.length - 1
          )
        ]
    )
    .join("");
}

console.log(textpand("unko", 140, 10));