Nodejs Array Flatten flatten()

Method Source Code

/*/*from  w  w w  .  ja v a  2 s  .  c  o m*/
 * flatten an array
 * author: StrayBugs
 */

// will return a new array and the origin remains unchanged
Array.prototype.flatten = Array.prototype.flatten || function() {
  'use strict';
  var that = this;
  for (var i = 0; i < that.length; i += 1) {
    if (Array.isArray(that[i])) {
      that = that.concat.apply([], that);
      i -= 1;
    }
  }
  return that;
};
// same as `flatten`
Array.prototype.flatten1 = Array.prototype.flatten1 || function() {
  'use strict';
  var res = [];
  (function flatten(arr) {
    for (var i = 0; i < arr.length; i += 1) {
      if (Array.isArray(arr[i])) {
        flatten(arr[i]);
      } else {
        res.push(arr[i]);
      }
    }
  }(this));
  return res;
};
// will change the origin array
Array.prototype.flatten2 = Array.prototype.flatten2 || function() {
  'use strict';
  for (var i = 0; i < this.length; i += 1) {
    if (Array.isArray(this[i])) {
      this.splice.apply(this, [i, 1].concat(this[i].flatten()));
    }
  }
  return this;
};

var a = [1, 2, [3, 4, [5, 6]]];
console.log(a.flatten()); // [ 1, 2, 3, 4, 5, 6 ]
console.log(a); // [ 1, 2, [ 3, 4, [ 5, 6 ] ] ]

console.log(a.flatten1()); // [ 1, 2, 3, 4, 5, 6 ]
console.log(a); // [ 1, 2, [ 3, 4, [ 5, 6 ] ] ]

console.log(a.flatten2()); // [ 1, 2, 3, 4, 5, 6 ]
console.log(a); // [ 1, 2, 3, 4, 5, 6 ]

Related

1. flatten()

   Array.prototype.flatten = function() {
     return this.reduce(function(res, el) {
       if(el.constructor == Array) {
         el.forEach(function(sub_el) {
           res.push(sub_el);
         })
       } else {
         res.push(el);
       return res;
     }, []);
   

2. flatten()

   Array.prototype.flatten = function () {
     var toReturn = [];
     for (var i = 0, len = this.length; i < len; i++) {
       if (this[i] instanceof Array) {
         toReturn = toReturn.concat(this[i].flatten());
       } else {
         toReturn.push(this[i]);
     return toReturn;
   };
   

3. flatten()

   Array.prototype.flatten = function() {
     return this.reduce(function(a,b) {
       return a.concat(b)
     }, [])
   

4. flatten()

   Array.prototype.flatten = function(){
       var flattenArray = [];
       for (var el in this) {
           var currElement = this[el];
           if (Object.prototype.toString.call(currElement) === '[object Array]' ) {
               for (var i in currElement) {
                   flattenArray.push(currElement[i]);
           } else {
   ...
   

5. flatten()

   var slice = Array.prototype.slice;
   Array.prototype.flatten = function () {
     var obj, result = [];
     for (var i = 0, l = this.length; i < l; ++i ) {
       obj = this[ i ];
       if ( Array.isArray( obj ) ) {
         result = result.concat( obj.flatten() );
       } else {
         result[ result.length ] = obj;
   ...
   

6. flatten()

   var arrays = [[1, 2, 3], [4, 5], [6]];
   console.log(arrays.reduce(function(a, b){
     return a.concat(b);
   }));
   Array.prototype.flatten = function(){
     return this.reduce(function(a, b){
       if(!Array.prototype.isPrototypeOf(a))
         a = [a];
       else
   ...
   

7. flatten(array)

   Array.prototype.flatten = function(array) {
     return this.reduce((prev, next) => prev.concat(next), []);
   };
   

8. flatten(func)

   Array.prototype.flatten = function (func) {
     var result = [];
     forEach(this, function (element) {
       forEach(func(element), function (child) {
         result.push(child);
       });
     });
     return result;  
   

9. flatten(nil)

   Array.prototype.flatten = function(nil){
       result = new Array();
       for(var i = 0; i < this.length; i++){
     item = this[i];
     if($.isArray(item)) for(var j = 0; j < item.length; j++) result.push(item[j]);
     else result.push(item);
       return result;
   };
   ...