符合条件的对象的JavaScript搜索数组

JavaScript search array of objects on condition

本文关键字：搜索数组 JavaScript 对象条件更新时间：2023-09-26

我有一个测试对象数组，如下所示，每个测试对象都有一个popupTime键：

var quizzes = {
    "quizzes": [
        {
            "_id": "546060033ea982a04f2e1859",
            "popupTime": 2.24,
            "lectureId": 5008,
            "__v": 0,
            "questions": [
                {
                    "title": "Which is the capital of India",
                    "_id": "546060033ea982a04f2e185f",
                    "answerswers": [
                        {
                            "answerswer": "Delhi",
                            "_id": "546060033ea982a04f2e1863",
                            "correct": true
                        },
                        {
                            "answerswer": "Bangalore",
                            "_id": "546060033ea982a04f2e1862",
                            "correct": false
                        },
                        {
                            "answerswer": "Mumbai",
                            "_id": "546060033ea982a04f2e1861",
                            "correct": false
                        },
                        {
                            "answerswer": "Chennai",
                            "_id": "546060033ea982a04f2e1860",
                            "correct": false
                        }
                    ]
                },
                {
                    "title": "Where is housing located? ",
                    "_id": "546060033ea982a04f2e185a",
                    "answerswers": [
                        {
                            "answerswer": "Delhi",
                            "_id": "546060033ea982a04f2e185e",
                            "correct": false
                        },
                        {
                            "answerswer": "Bangalore",
                            "_id": "546060033ea982a04f2e185d",
                            "correct": true
                        },
                        {
                            "answerswer": "Mumbai",
                            "_id": "546060033ea982a04f2e185c",
                            "correct": false
                        },
                        {
                            "answerswer": "Chennai",
                            "_id": "546060033ea982a04f2e185b",
                            "correct": false
                        }
                    ]
                }
            ]
        },
      {
    "_id" : "5460640d1e8743ee61413690",
    "popupTime" : 169,
    "lectureId" : 5008,
    "questions" : [ 
        {
            "title" : "Is this the 2nd quiz in same lecture?",
            "_id" : "5460640d1e8743ee61413691",
            "answerswers" : [ 
                {
                    "answerswer" : "True",
                    "_id" : "5460640d1e8743ee61413693",
                    "correct" : true
                }, 
                {
                    "answerswer" : "False",
                    "_id" : "5460640d1e8743ee61413692",
                    "correct" : false
                }
            ]
        }
    ],
    "__v" : 0
}
    ]
};

扫描整个测试对象，得到一个满足popupTime = 169的对象并将其保存在另一个对象中，哪种方法最有效？

在重复调用的执行时间方面效率很高。我将多次对同一个数组执行相同的操作来检查条件。

我建议您使用一个单独的array，其目的是通过popupTime来index your object。因此创建一个单独的array:

var indexArray = [];

每次在quizzes中插入新的Object时，也要在此数组中插入popupTime：

indexArray.push(yournewObject.popupTime);

然后你可以使用Array.prototype.indexOf方法找到你的元素：

var yourSearchedObject = quizzes[indexArray.indexOf(169)];

您可以通过popupTime对集合进行索引，以执行O(1)查找。假设popupTime是唯一的。

function index(collection, by) {
   var cache = {}, i = 0, len = collection.length, item;
   for(; i < len; ++i) { //for is faster than forEach and it's friends
      item = collection[i];
      cache[item.key] = item;
   }
   return function findOne(key) {
       return cache[key];
   }
}
var findByPopupTime = index(quizzes.quizzes, 'popupTime');
var quiz169 = findByPopupTime(169);