JSFiddle - React, Tailwind, and code Playground

JavaScript

const tree = {
  value: 1,
  next: [
    {
      value: 4,
      next: [
        {
          value: 5,
          next: []
        },
        {
          value: 3,
          next: [
            {
              value: 6,
              next: []
            }
          ]
        }
      ]
    },
    {
      value: 10,
      next: []
    }
  ]
};


const sumAllValue = (tree) => {
  let result = 0;
  
  const DFS = (tree) => {
    result += tree.value;
    
    if (tree.next.length) {
      tree.next.forEach((child) => {
        DFS(child)
      });
    }
  };
  
  DFS(tree);
  
  return result
};



alert(sumAllValue(tree));