查找深嵌套数组深度

Question

I have a nested array. Like below: I want to find the depth of this nested array, which means the child element has most deep nested children.

let arr = [
   {
     name: 'tiger',
     children: [{
       name: 'sinba',
       children: [{
         name: 'cute',
         children: []
        }]
      }]
    },
    {
      name: 'lion',
      children: []
    }
]

In this case, the depth is 3 , the tiger has 3 level. So the depth is 3

How could i achieve this? I try to use recursive, but don't know how to find the element which has most nested children.

Thanks in advance.

Answer 1

Assuming that there are no circular references, you could try something like this

 let arr = [{ name: 'tiger', children: [{ name: 'sinba', children: [{ name: 'cute', children: [] }] }] }, { name: 'lion', children: [] } ] function count(children) { return children.reduce((depth, child) => { return Math.max(depth, 1 + count(child.children)); // increment depth of children by 1, and compare it with accumulated depth of other children within the same element }, 0); //default value 0 that's returned if there are no children } console.log(count(arr))

Our function would not work if there were some circular references, so there might be a need to adjust it accordingly. Detecting circular references is a whole ordeal. If nothing is done about it, the function will throw a Maximum call stack size exceeded error.

In order to handle it without any additional functionality implementation you could use already existing native JSON.stringify to do so. The stringify option will throw an exception only if you try to serialize BigInt values which we can handle ourselves or when objects are cyclic, which is excatly what we wanted.

 let arr = [{ name: 'tiger', children: [] }] function testCircular(arr){ try { BigInt.prototype.toJSON = function() { return this.toString() } // Instead of throwing, JSON.stringify of BigInt now produces a string JSON.stringify(arr); return false; } catch (e) { // will only enter here in case of circular references return true; } } function count(children) { if (testCircular(children)) return Infinity; return children.reduce((depth, child) => { return Math.max(depth, 1 + count(child.children)); // increment depth of children by 1, and compare it with accumulated depth of other children within the same element }, 0); //default value 0 that's returned if there are no children } console.log(count(arr)) // normally counting arr[0].children = arr; // creates circular reference console.log(count(arr)) // counting for circular