implementing some lodash functions

lodash_practice.js

// modification version
function once(f) {
  let hasRun = false;
  let result;
  return () => {
    if (!hasRun) {
      result = f();
      hasRun = true;
    }
    return result;
  };
}

function init() {
  console.log('initializing');
}

const t = once(init);

t();
t();

function rearg(f, argumentIndeces) {
  return (...args) => {
    const reordered = _.map(argumentIndeces, index => _.nth(args, index));
    return f(...reordered);
  };
}

function orig(a, b, c) {
  return [a, b, c];
}

const rearged = rearg(orig, [2, 0, 1]);

console.log(rearged('b', 'c', 'a'));

function after(n, f) {
  let runs = n;
  return () => {
    if (runs <= 1) {
      return f();
    } else {
      runs -= 1;
    }
  };
}