Day-7 (2629. Function Composition).js

/**
 * @param {Function[]} functions
 * @return {Function}
 */
var compose = function(functions) {
  return function(x) {
    // return functions.reduceRight((acc, fn) => fn(acc), x);

    if(functions.length == 0) return x;
    let input = x;
    for(let i = functions.length-1; i>=0; i--){
      const currFunc = functions[i];
      input = currFunc(input);
    }
    return input;
  };
};

/**
 * const fn = compose([x => x + 1, x => 2 * x])
 * fn(4) // 9
 */