Nodejs Array Filter filterSyncasync (callback, thisArg)

Method Source Code

Array.prototype.filterSync = async function (callback, thisArg) {
  let filterResult = await Promise.all(this.map(callback))
  // > [true, false, true]

  return this.filter((_, index) => filterResult[index])
}

Related

1. cs142filter(element, func)

   'use strict'
   Array.prototype.cs142filter = function(element, func) {
     var result = [];
     var array = Object(this);
     var length = array.length;
     for (var i = 0; i < length; i++) {
       var val = array[i];
       if (func.call(undefined, element, val)) {
         result.push(val);
   ...
   

2. customFilter(fn)

   Array.prototype.customFilter = function(fn) {
     let results = [];
       for (let i = 0; i < this.length; i++) {
           let itemExists = fn(this[i]);
           if (itemExists) {
               results.push(this[i]);
     return results;
   ...
   

3. filterByField(field, key)

   Array.prototype.filterByField = function(field, key) {
     var newArray = [];
     for (var i = 0; i < this.length; i++) {
       if (this[i][field] == key) {
         newArray.push(this[i]);
     return newArray;
   };
   ...
   

4. filterByField(field, value)

   Array.prototype.filterByField = function (field, value)
       var list = this;
       var listReturn = [];
       list.forEach(function(item)
           if (item[field] === value)
               listReturn.push(item);
   ...
   

5. filterEmpty()

   Array.prototype.filterEmpty = function ()
       var arr = this;
       var i = arr.length;
       while (i--)
           if (arr[i] instanceof Array)
               arr[i] = arr[i].filterEmpty();
   ...
   

6. filterUnique()

   Array.prototype.filterUnique = function() {
       'use strict';
       var arr = [];
       var orig = this;
       orig.forEach(function(a, i) {
           if (arr.indexOf(a) < 0) {
               arr.push(a);
           } else {
               orig.splice(i, 1);
   ...
   

7. mfilter(fun)

   Array.prototype.mfilter =  function (fun) {
     var filtered = [];
     for(let i = 0; i < this.length; i++) {
       if (fun(this[i], i, this)) filtered.push(this[i]);
     return filtered;
   };
   var returnarr = [1,2,3,4,5,6].mfilter(function(element, index, arr) {
     return element > 5;
   ...
   

8. single(filter)

   Array.prototype.single = function(filter) {
     var matches = this.filter(filter);
     if (matches.length == 0) {
       throw new Error("Expected 1 but found 0");
     if (matches.length > 1) {
       throw new Error("Expected 1 but found many");
     return matches[0];
   ...
   

9. singleOrNone(filter)

   Array.prototype.singleOrNone = function(filter) {
     var matches = this.filter(filter);
     if (matches.length > 1) {
       throw new Error("Expected 1 but found many");
     if (matches.length == 0) {
       return null;
     return matches[0];
   ...