JavaScript过滤方法-仅返回第一个对象

Question

Using the filter() method in JavaScript, is it possible to return only the first instance that passes the test? Once I find first object in my cars array, I'd like to move this object from its current position to the beginning of the cars array.

Code:

     cars.filter(function(car) {

        var fareType = car.data("fareType");
        var partnerCode = car.data("partnerCode");

        if (fareType == "DEAL" && partnerCode == "AV")
        {
            // get first instance only and move element to beginning of array
        }

        if (fareType == "DEAL" && partnerCode == "BU")
        {
            // also get first instance where partnerCode == BU only and move element to beginning of array 
           // If dataPrice is less than dataPrice for partner AV, move to first position, else move to second position
        }
    });

Answer 1

I would use .findIndex and .splice :

let index = cars.findIndex(function(car) {
    var fareType = car.data("fareType");
    var partnerCode = car.data("partnerCode");
    return (fareType == "DEAL" && partnerCode == "AV");
});
if (index !== -1) {
    let car = cars[index];
    cars.splice(index, 1);
    cars.unshift(car);
    /*
     * this could be reduced to:
     *
     *     cars.unshift(...cars.splice(index, 1));
     *
     * at the sake of clarity
     */
}

index = cars.findIndex(function(car) {
    return fareType == "DEAL" && partnerCode == "BU";
});
if (index !== -1) {
    let car = cars[index];
    cars.splice(index, 1);
    if (car.data('price') < cars[0].data('price')) {
        cars.unshift(car);
    } else {
        cars.splice(1, 0, car);
    }
}

Answer 2

You can use findIndex()

var selectedIndex = cars.findIndex(function(car) {
    return car.data("fareType")== "DEAL" && car.data("partnerCode")== "AV";
});

if (selectedIndex > -1) {
   cars = [cars[selectedIndex], ...cars.slice(0, selectedIndex), ...cars.slice(selectedIndex + 1)
}

Answer 3

You could do something like:

let indexToGoFirst = 0;

cars.some((car, index) => {
  const fareType = car.data('fareType');
  const partnerCode = car.data('partnerCode');

  if (fareType == 'DEAL' && partnerCode == 'AV') {
    indexToGoFirst = index;
    return True
  }
})

cars[0] = cars[indexToGoFirst];

The .some() checks if anything in the array matches the condition, and will stop looping when the condition is met, so you can use that to set the first element.

Answer 4

Find index and create new array with element first

var index = cars.findIndex(function(car) {
        var fareType = car.data("fareType");
        var partnerCode = car.data("partnerCode");

        // get first instance only and move element to beginning of array

        return fareType == "DEAL" && partnerCode == "AV";

    });

var newCars = index > 0? [cars[index]].concat(cars.slice(0, index)).concat(cars.slice(index + 1): cars;