Nodejs Array Group By groupBy(callback)

Method Source Code

Array.prototype.groupBy = function(callback) {
    let obj = {}//ww  w  . j a va 2s  .  c om
    this.forEach(el => {
        let index = callback(el)
        if (!obj.hasOwnProperty(index)) {
            obj[index] = []
        }
        obj[index].push(el)
    })
    return obj
}

Related

1. groupBy(callback)

   Array.prototype.groupBy = function(callback){
   var results = {};
     this.forEach(function (el){
       var key = callback(el);
       if (key in results === false) {
         results[key] = [];
       results[key].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;
   ...