flatten array

flatten_array.js

var flattenWithReduce = (function () {
  function flatten(prev, curr, i, a) {
    var result;
    if(Array.isArray(curr)) {
      result = prev.concat(curr.reduce(flatten, []));
    } else {
      result = prev.concat(curr);
    }
    return result;
  }
	
  return function (array) {
    if(!Array.isArray(array)) throw new TypeError("the first argument is not a Array");
    return array.reduce(flatten, []);
  }
})();

// 大同小异
function flattenWithApply(array) {
  if(!Array.isArray(array)) throw new TypeError("the first argument is not a Array");
  var result = [];
  array.forEach(function (e, i, a) {
    if(Array.isArray(e)) {
      Array.prototype.push.apply(result, flattenWithApply(e));
    } else {
      result.push(e);
    }
  });
  return result;
}