var obj = [{
  id: 1,
  name: 'abc',
  child: [{
    id: 2,
    name: 'xyz',
    child: [{
      id: 3,
      name: 'abcd',
      child: []
    }, {
      id: 3,
      name: 'abcd',
      child: []
    }]
  }]
}, {
  id: 100,
  name: 'dfsdfdsf',
  child: [{
    id: 101,
    name: 'xsdfsfyz',
    child: [{
      id: 102,
      name: 'sdfsfsdfsd',
      child: []
    }, {
      id: 103,
      name: 'sdfsdfsfd',
      child: []
    }]
  }]
}];


function recursion(input, arr = []) {
  if (!input.length) {
    return arr;
  }
  input.forEach(e => {
    arr.push({
      id: e.id,
      name: e.name
    });
    recursion(e.child, arr);
  });
  return arr;
}
console.log(recursion(obj, []));