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How to count a depth level of nested JavaScript objects?
We have an array of objects, which further have nested objects like this −
const arr = [{
id: 0, children: []
}, {
id: 1, children: [{
id: 2, children: []
}, {
id: 3, children: [{
id: 4, children: []
}]
}]
}];Our job is to write a recursive function, say assignDepth() that takes in this array and assigns depth property to each nested object. Like the object with id 0 will have depth 0, id 1 will have depth 1 as well, and since id 2 and id 3 are nested inside id 1 they will have depth 1 and id 4 which is further nested inside id 3 will have depth 2.
Therefore, let’s write the code for this function. It’s a simple recursive function which iterates over sub objects repeatedly until it reaches the end of the array −
Example
const arr = [{
id: 0, children: []
}, {
id: 1, children: [{
id: 2, children: []
}, {
id: 3, children: [{
id: 4, children: []
}]
}]
}];
const assignDepth = (arr, depth = 0, index = 0) => {
if(index < arr.length){
arr[index].depth = depth;
if(arr[index].children.length){
return assignDepth(arr[index].children, depth+1, 0);
};
return assignDepth(arr, depth, index+1);
};
return;
};
assignDepth(arr);
console.log(JSON.stringify(arr, undefined, 4));Output
The output in the console will be −
[
{
"id": 0,
"children": [],
"depth": 0
},
{
"id": 1,
"children": [
{
"id": 2,
"children": [],
"depth": 1
},
{
"id": 3,
"children": [
{
"id": 4,
"children": [],
"depth": 2
}
],
"depth": 1
}
],
"depth": 0
}
]
Updated on: 25-Aug-2020
2K+ Views
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