underscore-es/before.js

javaScript's functional programming helper library for ES6 and beyond.

// `_before` : (ahem) a function's function
// -----------------------------------------

// Returns a function that will only be executed up to (but not including) the Nth call.
export default function (times, func) {
  var memo;
  return function () {
    if (--times > 0) {
      memo = func.apply(this, arguments);
    }
    if (times <= 1) func = null;
    return memo;
  };
}