Prune tree

prune.js

function prune(tree, condition)
{
  const children = tree.children
    .map(
      tree => prune(tree, condition)
    )
    .filter(
      tree => tree != null
    );

    return (condition(tree) || children.length > 0)
      ? Object.assign({}, tree, { children: children })
      : null;
}

function includes(string) {
  return ({ name }) => name.includes(string);
}

const deps =  {
  name: "Overall",
  children: [
    {
      name: "England",
      children: [
        {
          name: "London",
          children: [
            {
              name: "Manu",
              children: [

              ]
            },
          ]
        },
        {
          name: "Manchester",
          children: [
          ]
        },
      ]
    },
    {
      name: "Poland",
      children: [
        {
          name: "Lądek Zdroj",
          children: [
          ]
        },
      ]
    },
  ]
};

let pruned = prune(
  deps, includes("an")
);

console.log(
  JSON.stringify(
    { i: deps, p: pruned }
  )
);