如何使用 UnderscoreJS 进行条件过滤

Question

我只想根据条件拉出一个数组元素。

我尝试了 Underscore.js 方法，例如 _.filter 和 _.where 方法，但无法获得所需的输出。

为了更清楚，我不想要价格 > 80 的汽车对象。

我尝试了下面的代码并得到了一个空数组：

var carsArray = [{
    "name": "Record1",
    "bookings": [{
        "price": 50,
        "actualPrice": 70,
    }]
}, {
    "name": "Record2",
    "bookings": [{
        "price": 60,
        "actualPrice": 100,
    }]
}, {
    "name": "Record3",
    "bookings": [{
        "price": 100,
        "actualPrice": 110,
    }]
}];

var availableCars = _.filter(carsArray, function (items) {
    return _.filter(items, function (cars) {
        return(cars.price <= 80);
    });
});

Answer 1

对于bookings数组中的多个元素

如果bookings数组中有多个元素，检查任意元素是否满足条件Array#some可以使用

carsArray.filter(car => car.bookings.some(booking => booking.price <= 80));

查看是否全部订车价格在80以下Array#every可以使用

carsArray.filter(car => car.bookings.every(booking => booking.price <= 80));

现场演示：

var carsArray = [{
    "name": "Record1",
    "bookings": [{
        "price": 50,
        "actualPrice": 70,
    }, {
        "price": 40,
        "actualPrice": 70
    }]
}, {
    "name": "Record2",
    "bookings": [{
        "price": 60,
        "actualPrice": 100,
    }, {
        "price": 90,
        "actualPrice": 160
    }]
}, {
    "name": "Record3",
    "bookings": [{
        "price": 100,
        "actualPrice": 110,
    }, {
        "price": 120,
        "actualPrice": 200
    }]
}];

var atLeastOne = carsArray.filter(car => car.bookings.some(booking => booking.price <= 80));
var allCars = carsArray.filter(car => car.bookings.every(booking => booking.price <= 80));

document.getElementById('some').innerHTML = JSON.stringify(atLeastOne, 0, 4);
document.getElementById('every').innerHTML = JSON.stringify(allCars, 0, 4);

<strong>For any of the car bookings less than or equal to 80</strong>
<pre id="some"></pre>

<hr />
<strong>For all of the car bookings less than or equal to 80</strong>
<pre id="every"></pre>

对于 bookings 数组中的单个元素

您可以使用 JavaScript Array#filter with Arrow function 如下。

carsArray.filter(car => car.bookings[0].price <= 80);

var carsArray = [{
    "name": "Record1",
    "bookings": [{
        "price": 50,
        "actualPrice": 70,
    }]
}, {
    "name": "Record2",
    "bookings": [{
        "price": 60,
        "actualPrice": 100,
    }]
}, {
    "name": "Record3",
    "bookings": [{
        "price": 100,
        "actualPrice": 110,
    }]
}];

var filteredArr = carsArray.filter(car => car.bookings[0].price <= 80);

console.log(filteredArr);
document.getElementById('result').innerHTML = JSON.stringify(filteredArr, 0, 4);

<pre id="result"></pre>

如果bookings数组只有一个元素，数据的格式可以改为

var carsArray = [{
    "name": "Record1",
    "bookings": {
        "price": 50,
        "actualPrice": 70,
    }
}, {
    "name": "Record2",
    "bookings": {
        "price": 60,
        "actualPrice": 100,
    }
}, {
    "name": "Record3",
    "bookings": {
        "price": 100,
        "actualPrice": 110,
    }
}];

var filteredArr = carsArray.filter(car => car.bookings.price <= 80);

Answer 2

下面是使用 underscorejs 的方法

var availableCars = _.filter(carsArray, function(car) {
    return _.any(car.bookings, function(booking) {
        return booking.price <= 80; 
    });
});

这是在 es6 中的实现方式

var availableCars = carsArray.filter(car => car.bookings.some(booking => booking.price <= 80));

这当然是如果一辆车可能有多个预订，并且至少 1 个预订 <= 80 元

Answer 3

试试这个：

var availableCars = _.filter(carsArray, function(item){
    return (item.bookings.price <= 80);
    });
});

Answer 4

我想你想要的是这个：

var availableCars = _.filter(carsArray, function(car){
  return _.every(car.bookings, function(booking) {
    return booking.price <= 80;
  });
});

我假设每辆车可以有多个预订，并且如果 none 的预订超过 80，您只需要一辆车。

Answer 5

我想我会加入一些更接近要求的东西

我不想要价格 > 80 的汽车对象

function expensiveBooking(booking){
    return booking.price > 80;
}

function carHasExpensiveBooking(car){
    return _.some(car.bookings, expensiveBooking);
}

var result = _.reject(carsArray, carHasExpensiveBooking);

如何使用 UnderscoreJS 进行条件过滤

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