gistfile1.txt

var data = [
  ['strong', 0, 5],
  ['span', 0, 5],
  ['em', 2, 5]
];

var text = 'hello';

//function vtext(t) {}
//function vnode(name, attrs, chldren) {}

/*[
  vnode('strong', {}, [
    vtext('he'),
    vnode('span', {}, [
      vtext('llo')
    ])
  ])
]*/

var vtree = [];
var current = null;

data.forEach(function(x) {
  if (current == null || current !== null && !(x[1] >= current.start && x[2] <= current.end)) {
    current = {
      name: x[0],
      children: []
    };
    
    vtree.push(current);
  } else if (current !== null && x[1] >= current.start && x[2] <= current.end) {
    var newCurrent = {
      name: x[0],
      children: []
    };
    
    current.children.push(newCurrent);
    current = newCurrent;
  }
});

console.log(vtree);