partialApplication.js

const partial1 = function partial(fn) {
    // Drop the function from the arguments list and
    // fix arguments in the closure.
    const args = [].slice.call(arguments, 1);

    // Return a new function with fixed arguments.
    return function() {
      // Combine fixed arguments with new arguments
      // and call fn with them.
      const combinedArgs = args.concat(
        [].slice.call(arguments));
      return fn.apply(this, combinedArgs);
    };
  };

const partial2 = function partial(fn, ...args1) {
    return function(...args2) {
      return fn(...args1, ...args2);
    };
  };

const partial3 = function partial(fn, ...args) {
    return fn.bind(null, ...args);
};