Pushing entries from an array within an array to another array within an array for JavaScript?

Question

I have an array of information sub-divided into sub-arrays. I wish to then apply modifiers, which are also an array within an array.

  var legonisUnits = [
    "/pa/units/land/aa_missile_vehicle/aa_missile_vehicle.json",
    "/pa/units/land/assault_bot_adv/assault_bot_adv.json",
  ];
  var foundationUnits = [
    "/pa/units/air/air_factory_adv/air_factory_adv.json",
    "/pa/units/air/air_factory/air_factory.json",
  ];

  var factionUnits = [
    legonisUnits,
    foundationUnits,
  ];

  var legonisCost = [];
  var foundationCost = [];
  var effeciencyTech = [legonisCost, foundationCost];

  var costBuff = function(faction) {
    _.forEach(faction, function(unit) {
      _.forEach(unit, function(unit) {
        effeciencyTech[0].push({
          file: unit,
          path: "build_metal_cost",
          op: "multiply",
          value: 0.75,
        })
      })
    })
  }
  _.forEach(factionUnits, costBuff(factionUnits))

Where I'm stuck is how to change the array being pushed to within efficiencyTech whenever I switch array within factionUnits.

c69 · Accepted Answer · 2020-07-15 21:42:56Z

1

If you use second parameter of array iterator forEach - (i in the code below), then your task becomes much simpler:

var units = [[], []]; // replace with your own init
var efficiency = [[], []];

units.forEach((faction, i) => {
    efficiency[i] = faction.map(unit => ({
        file: unit,
        path: 'build_metal_cost',
        op: 'multiply',
        value: '0.75'
    })
));

answered Jul 15, 2020 at 21:42

c69

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1 Comment

Quitch Over a year ago

Ran a quick test and this seems to be precisely what I need, and much cleaner too! Unfortunately I can't use arrow operators, because es5, but that's an easy conversion.

Barmar · Accepted Answer · 2020-07-15 21:55:18Z

0

The callback function in _.forEach() receives the array index as the second argument. You can use that to index into effeciancyTech.

You also shouldn't call _.forEach() inside costBuff. You're already looping over the factions because you're calling costBuff in in _.forEach().

var legonisUnits = [
  "/pa/units/land/aa_missile_vehicle/aa_missile_vehicle.json",
  "/pa/units/land/assault_bot_adv/assault_bot_adv.json",
];
var foundationUnits = [
  "/pa/units/air/air_factory_adv/air_factory_adv.json",
  "/pa/units/air/air_factory/air_factory.json",
];

var factionUnits = [
  legonisUnits,
  foundationUnits,
];

var legonisCost = [];
var foundationCost = [];
var effeciencyTech = [legonisCost, foundationCost];

var costBuff = function(faction, index) {
  _.forEach(faction, function(unit) {
    effeciencyTech[index].push({
      file: unit,
      path: "build_metal_cost",
      op: "multiply",
      value: 0.75,
    })
  })
}
_.forEach(factionUnits, costBuff)
console.log(effeciencyTech);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.19/lodash.min.js"></script>

edited Jul 15, 2020 at 21:55

answered Jul 15, 2020 at 21:43

Barmar

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2 Comments

Quitch Over a year ago

Unfortunately this seems to result in file becoming one character from the array entry e.g. / then p then a, etc.

Barmar Over a year ago

costBuff() doesn't need the first _.forEach(), because it's being called from _.forEach().

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