Object graph walker

walk.js

// Walk an object graph, calling the visit function with
// value, key, and object at each level.
function walk (o, visit) {
  visit(o, '', o)
  if (o && (Array.isArray(o) || Object(o) === o)) {
    let stack = [ o ]
    while (stack.length) {
      let obj = stack.shift()
      for (let k in obj) {
        const v = obj[k]
        if (v && (Array.isArray(v) || Object(v) === v)) {
          stack.push(v)
        }
        visit(v, k, obj)
      }
    }
  }
}