Looping Through an Object (Tree) Recursively

looping through an object (tree) recursively

You're looking for the for...in loop:

for (var key in foo)
{
    if (key == "child")
        // do something...
} 

Be aware that for...in loops will iterate over any enumerable properties, including those that are added to the prototype of an object. To avoid acting on these properties, you can use the hasOwnProperty method to check to see if the property belongs only to that object:

for (var key in foo)
{
    if (!foo.hasOwnProperty(key))
        continue;       // skip this property
    if (key == "child")
        // do something...
}

Performing the loop recursively can be as simple as writing a recursive function:

// This function handles arrays and objects
function eachRecursive(obj)
{
    for (var k in obj)
    {
        if (typeof obj[k] == "object" && obj[k] !== null)
            eachRecursive(obj[k]);
        else
            // do something... 
    }
}

recursive looping a object tree

You could use a function which takes the actual level and returns the callback for the array method.

Inside, the callback displays the key and call the function again with an increased level for next iteration.

function iter(level) {    return function (node)  {        console.log('node', level, node.key);        (node.children || []).forEach(iter(level + 1));    };}
var tree = [{ key: "parent1", id: "001", children: [{ key: "B", id: "002", children: [{ key: "C", id: "003", children: [{ key: "D", id: "004", children: [] }] }] }] }, { key: "parent2", id: "002", children: [{ key: "B", id: "002", children: [{ key: "C", id: "003", children: [{ key: "D", id: "004", children: [] }] }] }] }];
tree.forEach(iter(0));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Recursively looping through an object to build a property list

I made a FIDDLE for you. I am storing a stack string and then output it, if the property is of primitive type:

function iterate(obj, stack) {
        for (var property in obj) {
            if (obj.hasOwnProperty(property)) {
                if (typeof obj[property] == "object") {
                    iterate(obj[property], stack + '.' + property);
                } else {
                    console.log(property + "   " + obj[property]);
                    $('#output').append($("<div/>").text(stack + '.' + property))
                }
            }
        }
    }

iterate(object, '')

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Update: 17/01/2019

There used to be a different implementation, but it didn't work. See
this answer
for a prettier solution

Recursive loop through Javascript Object

You have a couple of issues; you should be traversing over the object, not its keys, and you should be checking if key === 'e', not target[key] !== 'e'. Also, you should check that target[key] is an object before attempting to traverse it:

const myObject = {
  x: {
    y: {
      z: {
        e: 'ddfg'
      }
    }
  }
};

function traverse(target) {
  for (const key in target) {
    if (key !== 'e' && typeof target[key] === 'object') {
      traverse(target[key]);
    } else {
      console.log(key, target[key]);
    }
  }
}

traverse(myObject);

How to iterate recursively over all children in nested objects

You are passing child which is an object and that is not iterable, you have to pass it's children. You can try checking if child having children array and then iterate children.

function selectActivePage(node) {
    for (let child of node) {
        child.folded = false;
        if(child.children && Array.isArray(child.children) && child.children.length > 0)
            selectActivePage(child.children)
    }
};

Recursively looping over an array of objects using a for loop

I figured out the problem I was having! I had to assign the value to a temp variable, then return it if it was not undefined.

  if (Array.isArray(tree)) {
    for (let item of tree) {
      let tmp = searchTreeForNode(item, nodeUuid);
      if (tmp !== undefined) {
        return tmp;
      }
    }
  }

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