reduction.js

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
exports.__esModule = true;
var reduce_1 = __importDefault(require("lodash/reduce"));
function testReduction() {
    var tempArray = [
        { a: 'foo', b: 'bar' },
        { a: 'baz', b: 'quux' }
    ];
    var reduction = reduce_1["default"](tempArray, function (acc, value) {
        console.log("value: a='" + value.a + "', b='" + value.b + "'");
        console.log("acc before=" + JSON.stringify(acc));
        var newAcc = acc.set(value.a, value);
        console.log("acc after=" + JSON.stringify(acc));
        console.log("newAcc=" + JSON.stringify(newAcc));
        return acc;
    }, new Map());
    console.log("reduction=" + JSON.stringify(reduction));
}
testReduction();

reduction.ts

import reduce from 'lodash/reduce'

type ReductionTest = {
  a: string
  b: string
}

function testReduction () {
  const tempArray: ReductionTest[] = [
    { a: 'foo', b: 'bar' },
    { a: 'baz', b: 'quux' }
  ]
  const reduction = reduce(
    tempArray,
    (acc: Map<string, ReductionTest>, value: ReductionTest) => {
      console.log(`value: a='${value.a}', b='${value.b}'`)
      console.log(`acc before=${JSON.stringify(acc)}`)
      const newAcc = acc.set(value.a, value)
      console.log(`acc after=${JSON.stringify(acc)}`)
      console.log(`newAcc=${JSON.stringify(newAcc)}`)
      return acc
    },
    new Map<string, ReductionTest>()
  )
  console.log(`reduction=${JSON.stringify(reduction)}`)
}

testReduction()

% tsc --esModuleInterop reduction.ts && node reduction.js
value: a='foo', b='bar'
acc before={}
acc after={}
newAcc={}
value: a='baz', b='quux'
acc before={}
acc after={}
newAcc={}
reduction={}