JavaScript 搜索对象数组并返回父对象的索引

Question

I have been looking around for a JavaScript method to return the index of a value but I can't seem to find one that works.

I have the following code:

let topics = [
    {
        id: 1,
        name: 'Topic 1',
        children: [
            {
               id: 2,
               name: 'Subtopic 1.1'  <---- Searching for this value
            }
        ]
    }
];

Is there a method to use on the topics variable to search through the entire object array at once for the value of Subtopic 1.1 and then return the parent index, which in this case would be 0.

Answer 1

There isn't a single function, but you can nest an Array.prototype.find function inside an Array.prototype.findIndex without issue to achieve what you want ( findIndex to search through the parents, find to search through the children):

 let topics = [{ id: 1, name: 'Topic 1', children: [{ id: 2, name: 'Subtopic 1.1' // <---- Searching for this value }] }, { id: 2, name: 'Topic 6', children: [{ id: 5, name: 'Subtopic 1.7' }] }, { id: 3, name: 'Topic 9', children: [{ id: 4, name: 'Subtopic 1.192' }, { id: 28, name: 'Subtopic 999' }], }, ]; function findParentIndex(name) { return topics.findIndex(topic => topic.children.find(child => child.name === name)); } console.log(findParentId("Subtopic 1.192")); // 3 console.log(findParentId("Subtopic 1.1")); // 1 console.log(findParentId("Not in the list")); // -1

Answer 2

No.

You would iterate through children, then have a nested loop iterating through each index value. If you find a match, the incrementing variable from the parent loop is the index you want.

edit: code example

let topics = [
    {
        id: 1,
        name: 'Topic 1',
        children: [
            {
               id: 2,
               name: 'Subtopic 1.1' 
            },
            {
                id: 2,
                name: 'Subtopic 3.1' 
             },
             {
                id: 2,
                name: 'Subtopic 1.1' 
             },
             {
                id: 2,
                name: 'Subtopic 2.1' 
             },
             {
                id: 2,
                name: 'Subtopic 1.1' 
             }
     
            ]
    }
];


for (let i in topics[0]["children"]) {
        if (topics[0]["children"][i]["name"] == "Subtopic 1.1") {
            console.log(i)
        }
    
}

Answer 3

You can use array.findIndex()

 let topics = [{ id: 1, name: 'Topic 1', children: [{ id: 1,name: 'Subtopic 1.2' }, { id: 4,name: 'Subtopic 1.4' }, { id: 2, name: 'Subtopic 1.1' }] }]; const findIndexOf = val => { return topics[0].children.findIndex(e => e.name.trim() === val.trim()) } console.log(findIndexOf('Subtopic 1.1'))