Convert JSON object to HTML list structure

json_to_html_list.js

function isObject(obj) {
  var type = typeof obj;

  return (type === 'function' || type === 'object') && !!obj;
}

function isArray(obj) {
  return obj instanceof Array
}

function build(obj) {
  let list = [];

  Object.keys(obj).forEach((key, _) => {
    var v = obj[key];
    list.push('<ul>')

    if (isArray(v)) {
      list.push('<li>' + key + '</li>')

      v.forEach((k, _) => {
        list.push('<ul>')
        list.push(build(k))
        list.push('</ul>')
      })
    } else if (isObject(v)) {
      list.push('<li>' + key + '</li>')

      list.push('<ul>')
      list.push(build(v))
      list.push('</ul>')
    } else {
      list.push('<li>' + key + ':&nbsp;&nbsp;' + v + '</li>')
    }

    list.push('</ul>')
  })

  return list;
}