Chaining multiple filters if condition exist

Question

I'm trying to chain two filters, based in two ranges (arrays) of params that may also be empty, so it would be possible that f.ex. speedlimit=[]

var speedfilter =[240,300] var pricefilter = [80,120] var cars = [ {name:'Ferrari', maxspeed:240, price: 100}, {name:'Porsche', maxspeed:220, price: 90}, {name:'Bugatti', maxspeed:300, price: 500} ]; if (speedfilters) { return cars.filter(function (car) { return car.maxspeed >= speedfilter[0] && car.maxspeed <= speedfilter[1]; }) } else if (pricefilter) { return cars.filter(function (car) { return car.price >= pricefilter[0] && car.price <= pricefilter[1]; }) } else return cars

The result in the example above should output {name:'Ferrari', speed:240, price: 100}

What would be the way to do it with javascript filter? Thanks in advance!

is it possible that there is a minimum speed but no maximum speed? — zfrisch
– zfrisch, Commented Jul 13, 2018 at 15:59
Dont use else if, filter cars by speed limit first and assign to a variable, then filter that variable by price limit — hamidb80
– hamidb80, Commented Jul 13, 2018 at 16:03
Maybe the names were confusing, I just changed it. I just want to filter the objects whose maxspeed are within the first range, and then filter the output again with the price — Joe82
– Joe82, Commented Jul 13, 2018 at 16:04
I'm confused by speedlimit='' - that variable is nowhere in your code. Did you mean speedfilter=[]? — Jamiec
– Jamiec, Commented Jul 13, 2018 at 16:05

Fabrizio Calderan · Accepted Answer · 2018-07-13 16:37:03Z

You could create a filterCar method via prototype inheritance

Array.prototype.filterCar = function(feature, range) { return this.filter((el) => { // is the range defined? if (!!range.length) { return el[feature] >= range[0] && el[feature] <= range[1]; } else { return true; } }) }; var cars = [ {name:'Ferrari', speed:240, price: 100}, {name:'Porsche', speed:220, price: 90}, {name:'Bugatti', speed:300, price: 500} ]; var result1 = cars.filterCar('speed', [240, 300]) .filterCar('price', [80, 120])); var result2 = cars.filterCar('speed', [ ]) .filterCar('price', [80, 120])); console.log(result1); // [{name: "Ferrari", speed: 240, price: 100}] console.log(result2); /* [{name: "Ferrari", speed: 240, price: 100}, {name: "Porsche", speed: 220, price: 90}] */

filterCar on the prototype of Array.... doesn't quite feel "right". Could/should have just been a method call. Also doesnt cover the "if exists" requirement.
this is just an example about how to use filter function. Don't understand the downvote btw.
I didn't downvote, but isn't the main thrust of the question how to handle possibly empty ranges?
@Joe82 it now does via the if...else inside the filter BTW

Jamiec · Accepted Answer · 2018-07-13 16:15:21Z

You can wrap your filtering up into a re-usable method, and this can account for the filter not being available.

function filterCars(carsArray, property, rangeArray) { // if rangeArray is not supplied, or is empty, just return the unfiltered input if(!rangeArray|| rangeArray.length === 0) { return carsArray; } // otherwise filter according to logic return carsArray.filter(car => car[property] >= rangeArray[0] && car[property] <= rangeArray[1]); }

This can be chained, or for more readability called in sequence:

 function filterCars(carsArray, property, rangeArray) { if(!rangeArray|| rangeArray.length === 0) { return carsArray; } return carsArray.filter(car => car[property] >= rangeArray[0] && car[property] <= rangeArray[1]); } var speedfilter = []; // [240,300] var pricefilter = [80,120] var cars = [ {name:'Ferrari', maxspeed:240, price: 100}, {name:'Porsche', maxspeed:220, price: 90}, {name:'Bugatti', maxspeed:300, price: 500} ]; cars = filterCars(cars,"maxspeed",speedfilter); cars = filterCars(cars,"price",pricefilter); console.log(cars);

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