在另一个数组中的 JavaScript 对象数组中按属性查找对象

Question

我有一个名为mainarray 的数组，其中包含三个对象。在每个对象内部都有另一个名为innerarray 的数组，它有自己的三个对象。

如何在每个innerarray 中获取第二个对象的第一个属性？这可能吗？

mainarray: [{
    innerarray: [{
        property1: value1,
        property2: value2,
        property3: value3,
    }, {
        propertyiwant: value1,
        property2: value2,
        property3: value3,
    }, {
        property1: value1,
        property2: value2,
        property3: value3,
    }]
}, {
    innerarray: [{
        property1: value1,
        property2: value2,
        property3: value3,
    }, {
        propertyiwant: value1,
        property2: value2,
        property3: value3,
    }, {
        property1: value1,
        property2: value2,
        property3: value3,
    }]
}, { 
    innerarray: [{
        property1: value1,
        property2: value2,
        property3: value3,
    }, {
        propertyiwant: value1,
        property2: value2,
        property3: value3,
    }, {
        property1: value1,
        property2: value2,
        property3: value3,
    }]
}]

这个问题与From an array of objects, extract value of a property as array 完全不同。在这里，我试图在另一个数组中的数组中获取对象的属性。

Answer 1

mainarray.map(item => item.innerarray[1].propertyiwant);

或者，如果你只使用下划线和 es5

_.map(mainarray, function(item){
    return item.innerarray[1].propertyiwant
});

Answer 2

你可以试试下面的代码。如果它们存在，它将在每个子数组中为您带来每一秒（在第 2、第 4、第 6 ......等意义上）对象。如果您只对第二个对象感兴趣，那么只需替换整个e.innerarray.reduce(..。与e.innerarray[2] 分开。这将为您提供整个所需的第二个对象，然后您可以访问它的任何您喜欢的属性。

var mainarray = [{
    innerarray: [{
        property1: "value1",
        property2: "value2",
        property3: "value3",
    }, {
        propertyiwant: "value1",
        property2: "value2",
        property3: "value3",
    }, {
        property1: "value1",
        property2: "value2",
        property3: "value3",
    }]
}, {
    innerarray: [{
        property1: "value1",
        property2: "value2",
        property3: "value3",
    }, {
        propertyiwant: "value1",
        property2: "value2",
        property3: "value3",
    }, {
        property1: "value1",
        property2: "value2",
        property3: "value3",
    }]
}, { 
    innerarray: [{
        property1: "value1",
        property2: "value2",
        property3: "value3",
    }, {
        propertyiwant: "value1",
        property2: "value2",
        property3: "value3",
    }, {
        property1: "value1",
        property2: "value2",
        property3: "value3",
    }]
}],
mapped = mainarray.map(e => e.innerarray.reduce((p,c,i) => (i%2 && p.push(c),p),[]));
console.log(mapped);