Get the index of the array when array object matching condition-CodePudding

I have an array like this:

parent = [
    {'id':'id_1','level':'1-1','children':['id':'id_1','level':'1-1-0','children':[........]},
    {'id':'id_2','level':'2-2','children':['id':'id_1','level':'2-1-0','children':[........]}
]

How can I get the parent array index that match the condition of child array object

For example:

If (level == '2-1-0')

Output: 1

Expected Behaviour:

It should return 1 because level 2-1-0 present in 1'st index of parent array

Note: I tried like below

var index = parent .findIndex(data => data.level== result.level);

It will not check child array object

CodePudding user response：

Your provided array is wrong, but I think that you need something like this:

const parent = [
    {'id':'id_1','level':'1-1','children':[{'id':'id_1','level':'1-1-0'}]},
    {'id':'id_2','level':'2-2','children':[{'id':'id_1','level':'2-1-0'}]}
]

const index = parent.findIndex(p => p.children.find(c => c.level === '2-1-0') !== undefined);

console.log(index);

In the place of '2-1-0' you should put the index, that you want to check.

CodePudding user response：

It's a recursive problem, which can blow the stack for big arrays.

The script traverses the tree depth first and can be optimized to detect the requested level depth and only check that level, increasing the performance.

var weirdProblem = level => (carry, current, idx) => {
  // bail if already found 
  if (carry > -1) {
    return carry;
  }

  // check current item's children and return current idx if matching
  if (current.children.some(child => child.level === level)) {
    return idx;
  }

  // traverse current item's children
  return current.children.reduce(weirdProblem(level), -1);
};

var index = parent.reduce(weirdProblem('2-1-0'), -1);

did not test the script.

CodePudding user response：

Your parent array is malformed, I guess it should be a nested structure.

Since children may also contains more children, you will need recursion for a deep search.

const parent = [
    {"id": "id_1", "level": "1-1", "children": [{"id": "id_1", "level": "1-1-0", "children": []}]},
    {"id": "id_2", "level": "2-2", "children": [{"id": "id_1", "level": "2-1-0", "children": []}]}
];

function levelIndex(children, level) {
    return children.findIndex(child => child.level == level || levelIndex(child.children, level) >= 0);
}
    
const index = levelIndex(parent, "2-1-0");
console.log("Found index:", index)

CodePudding user response：

You need recursion

const findItemNested = (arr, level, nestingKey) => (
  arr.reduce((a, item, index) => {
    if (a) return a;
    if (item.level === level) return index;
    if (item[nestingKey]) return findItemNested(item[nestingKey], level, nestingKey)
  }, null)
);
const testArr = [
      {
        'id':'id_1',
       'level':'1-1',
       'children':[
         {'id':'id_1'},
         {'level':'1-1-0'},
         {'children':[]}
       ]
      },
      {'id':'id_2','level':'2-2','children':[{'id':'id_1'},{'level':'2-1-0'},{'children':[]}]}
  ];

const res = findItemNested(testArr, '2-1-0', "children");

console.log(res) //  1

CodePudding user response：

in .TS file:-

const parent = [
    {'id':'id_1',
     'level':'1-1',
     'children':[{'id':'id_1',
                  'level':'1-1-0'}]},
                 {'id':'id_2',
                  'level':'2-2',
                  'children':[{'id':'id_1',
                               'level':'2-1-0'}]}
]

const index = parent.filter(x => x.children.find(x => x.level === '2-1-0') !== undefined);

console.log(index);

Give this a try. I think it will work.