Question

在JavaScript中使用filter（）方法，是否可以仅返回通过测试的第一个实例？一旦我在汽车阵列中找到第一个物体，我想将此物体从当前位置移动到汽车阵列的开头。

代码：

#included

Answer 1

我会使用.findIndex和.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

您可以使用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

您可以执行以下操作：

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];

.some()检查数组中的任何内容是否与条件匹配，并在满足条件时停止循环，因此您可以使用它来设置第一个元素。

Answer 4

查找索引并使用元素

创建新数组

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;

JavaScript过滤方法 - 仅返回第一个对象

4 个答案: