Nodejs Array Group By groupBy(callback)

Method Source Code

Array.prototype.groupBy = function(callback){
var results = {};
  this.forEach(function (el){
    var key = callback(el);
    if (key in results === false) {
      results[key] = [];//from   w w  w  .  j a  v a2  s .c  o m
    }
    results[key].push(el);
 });
  return Object.keys(results).map(function(key) {
    return {
      key: key,
      values: results[key]
    };
  });
};

var grouped = [1,2,3,4,5,6,7,8,9,10].groupBy(function(v, i, arr){
  return (v % 2 === 0) ? 'even' : 'odd';
});

console.log(grouped);

Related

1. groupBy(callback)

   Array.prototype.groupBy = function(callback) {
       let obj = {}
       this.forEach(el => {
           let index = callback(el)
           if (!obj.hasOwnProperty(index)) {
               obj[index] = []
           obj[index].push(el)
       })
   ...
   

2. groupBy(callback)

   Array.prototype.groupBy = function(callback){
       this.reduce() 
   var result{}
   this.forEach(v, i, arr) = function(){}
   v, i, arr
   Array.prototype.groupBy = function(callback){ 
     var evens = Array.groupBy.forEach([9])
     if(Array.groupBy %2 === 0){
   ...
   

3. groupBy(fieldName)

   Array.prototype.groupBy = function (fieldName) {
       if (this.some(item => item.hasOwnProperty(fieldName))) {
           let uniqVal = this.map(item => item[fieldName]).filter((value, item, array) => array.indexOf(value) === item);
           let tempObj = {};
           uniqVal.map(item => tempObj[item] = []);
           this.forEach(item => {
               for (let name in tempObj) {
                   if (item[fieldName] == name) {
                       tempObj[name].push(item);
   ...
   

4. groupBy(fieldkey,fieldsums,fn)

   Array.prototype.groupBy=function(fieldkey,fieldsums,fn){
     var groups = _.groupBy(this,function(item){
       return item[fieldkey];
     });
     async.map(_.keys(groups)
       ,function(key,callback){
         var value = groups[key];
         var r = {};
         r[fieldkey] = key;
   ...
   

5. groupBy(fn)

   Array.prototype.groupBy = function (fn) {
     var result = {
     };
     for (var i = 0; i < this.length; i++)
       try {
         if (!result[fn(this[i])])
           result[fn(this[i])] = [
   ...