循环对象内的数组内的对象内的数组JavaScript

Question

我试图在数组内的对象内循环对象内的数组，我真的很困惑！

这是我的任务：

var arr = [
{
title: "Harry Potter",
categories: [
{
id: 39,
name: "Popular Books"
},
{
id: 3,
name: "Kids"
},
{
id: 79,
name: "All Books"
}
]
},


{
title: "Pride and Prejudice",
categories: [
{
id: 36,
name: "Classic Books"
},
{
id: 3,
name: "Woman"
},
{
id: 79,
name: "All Books"
}
]
}
]

如何获得只有“儿童”类别名称的书名？

现在我能想到的只有：

var find = function(arr){
  for(var i=0; i<arr.length; i++){
    for(var j=0; j<arr[i].categories; j++){
      console.log(arr[i].categories[j].name)
    }
  }
}

这是超级肮脏的，无论如何都不起作用。 谢谢！

Answer 1

您可以使用过滤器过滤那些类别与“儿童”匹配的数组元素，然后将它们的标题映射到一个新数组中。

arr.filter( i => i.categories.some(j => j.name ==="Kids") ).map(k => k.title )

var arr = [{
    title: "Harry Potter",
    categories: [{
        id: 39,
        name: "Popular Books"
      },
      {
        id: 3,
        name: "Kids"
      },
      {
        id: 79,
        name: "All Books"
      }
    ]
  },


  {
    title: "Pride and Prejudice",
    categories: [{
        id: 36,
        name: "Classic Books"
      },
      {
        id: 3,
        name: "Woman"
      },
      {
        id: 79,
        name: "All Books"
      }
    ]
  }
];

console.log(arr.filter(i => i.categories.some(j => j.name === "Kids")).map(k => k.title));

Answer 2

试一试：

var find = function(arr, name) {
    for (var i = 0; i < arr.length; i++) {
        for (var j = 0; j < arr[i].categories.length; j++) {
            if (arr[i].categories[j].name === name) {
                return arr[i].categories[j];
            }
        }
    }
}

find(arr, 'Kids')