Function depthOf

docs/src/javascripts/lifecycle.js:865–872

(id, memo)

    const byId = {};
    TRACE_SPANS.forEach((s) => (byId[s.id] = s));
    function depthOf(id, memo) {
      if (!memo) memo = {};
      if (memo[id] != null) return memo[id];
      const s = byId[id];
      if (!s || s.parent == null) memo[id] = 0;
      else memo[id] = depthOf(s.parent, memo) + 1;
      return memo[id];
    }
    const memo = {};
    const depths = {};
    TRACE_SPANS.forEach((s) => (depths[s.id] = depthOf(s.id, memo)));