带有Javascript的高级Array.prototype.filter

Question

I have an Javascript object like so...

var strategies = [{
    "strategy": {
        "category": "war"
    }
}, {
    "strategy": {
        "category": "farming"
    }
}]

I then have an array that indicates which results I'd like back. It can be any of the following: [] OR ["war"] ["farming"] OR ["war", "farming"] .

If we have the [] , I want to return no results. But if ["war", "farming"] I want to return both of the results above.

How do I accomplish this with Array.prototype.filter ? I saw this post , but couldn't reason through it.

strategies.filter((strategy) => 
  ????
)

Thanks for your help.

Answer 1

You can just check the value with indexOf :

var categories = ['war', 'farming'];

var filtered = strategies.filter((obj) => {
  return categories.indexOf(obj.strategy.category) > -1;
});

Answer 2

Your object, strategy was a wrapped object, so my first line was setting it to its inner strategy and then filter as needed.

var strategies = [{
    "strategy": {
        "category": "war"
    }
}, {
    "strategy": {
        "category": "farming"
    }
}]
var b = ["war", "farming"];
strategies.filter(function(strategy){
   strategy = strategy.strategy;
   for(var i in b){
     if (b[i] == strategy["category"]) {
        return true;
      }
  }
  return false;
});

Answer 3

Tests the input array to see if it's empty as per your requirements:

function filterObj(arr) {
  return !arr.length ?  arr :
  strategies.filter((el) => arr.indexOf(el.strategy.category) > -1);
}

filterObj(['war', 'farming'])

DEMO