How to do equivalent of LINQ SelectMany() just in javascript

Question

Unfortunately, I don\'t have JQuery or Underscore, just pure javascript (IE9 compatible).

I\'m wanting the equivalent of SelectMany() from LINQ functionality.

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Answer 1

for a simple select you can use the reduce function of Array.
Lets say you have an array of arrays of numbers:

var arr = [[1,2],[3, 4]];
arr.reduce(function(a, b){ return a.concat(b); });
=>  [1,2,3,4]

var arr = [{ name: "name1", phoneNumbers : [5551111, 5552222]},{ name: "name2",phoneNumbers : [5553333] }];
arr.map(function(p){ return p.phoneNumbers; })
   .reduce(function(a, b){ return a.concat(b); })
=>  [5551111, 5552222, 5553333]

Edit:
since es6 flatMap has been added to the Array prototype. SelectMany is synonym to flatMap.
The method first maps each element using a mapping function, then flattens the result into a new array. Its simplified signature in TypeScript is:

function flatMap(f: (value: A) => B[]): B[]

In order to achieve the task we just need to flatMap each element to phoneNumbers

arr.flatMap(a => a.phoneNumbers);