Sorting an array of objects with a variable filter

Question

Im trying to filter my array of objects by the current month. Using animal crossing fish as an example

const fishData = {
   "fish_name": "Barreleye",
   "price": "15,000",
   "location": "Sea",
   "shadow_size": "Small",
   "n_March": true,
   "n_3": true,

 },
 {
   "fish_name": "Coelacanth",
   "price": "15,000",
   "location": "Sea (Rainy Days)",
   "shadow_size": "Largest",
   "n_3": true,

 }
]

var today = new Date();
var currentMonth = today.getMonth();

var fishMonth = `n_ + ${currentMonth}`;
console.log(fishMonth);
var filteredFish = fishData.filter(function(i) {
    return i.fishMonth == true;
});

now by return if i put "n_3" instead of "fishMonth" the code runs fine. I've checked the "fishMonth" and it does return n_3. What would be stoping this from working?

mickl · Accepted Answer · 2020-04-15 21:02:01Z

1

There are unnecessay characeter in your fishMonth variable, it should be:

var fishMonth = `n_${currentMonth}`;

and you also want to read the object's key so there has to be return i[fishMonth] == true;, try:

const fishData = [{
   "fish_name": "Barreleye",
   "price": "15,000",
   "location": "Sea",
   "shadow_size": "Small",
   "n_March": true,
   "n_3": true,

 },
 {
   "fish_name": "Coelacanth",
   "price": "15,000",
   "location": "Sea (Rainy Days)",
   "shadow_size": "Largest",
   "n_3": true,

 }
]

var today = new Date();
var currentMonth = today.getMonth();

var fishMonth = `n_${currentMonth}`;
var filteredFish = fishData.filter(function(i) {
    return i[fishMonth] == true;
});
console.log(filteredFish);

answered Apr 15, 2020 at 21:02

mickl

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Comments

Nina Scholz · Accepted Answer · 2020-04-15 21:18:50Z

You need the right key value without space and + and the right property accessor with brackets.

You could take some more changes, for example get the month directly from the instance and return directly the value of the wanted property.

const
    fishData = [{ fish_name: "Barreleye", price: "15,000", location: "Sea", shadow_size: "Small", n_March: true, n_3: true }, { fish_name: "Coelacanth", price: "15,000", location: "Sea (Rainy Days)", shadow_size: "Largest", n_3: true }],
    fishMonth = `n_${(new Date).getMonth()}`,
    filteredFish = fishData.filter(fish => fish[fishMonth]);

console.log(filteredFish);

Finally, you could change the whole data structure and add the month as value to the objects and use something like a month property. This allowes to use a simple comparison with the value instead of using a compound key.

const
    fishData = [{ fish_name: "Barreleye", price: "15,000", location: "Sea", shadow_size: "Small", n_March: true, month: 3 }, { fish_name: "Coelacanth", price: "15,000", location: "Sea (Rainy Days)", shadow_size: "Largest", month: 3 }],
    fishMonth = (new Date).getMonth(),
    filteredFish = fishData.filter(({ month }) => month === fishMonth);

console.log(filteredFish);

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