Handy method to log or print information about objects while using marklogic

describeMarkLogicObjects.js

// helper function to get all method names including prototype inherited
function getMethods(obj) {
  let ms = getMethodsDups(obj)
  let uniq = ms.filter(
   (item, pos, self) => {
    return self.indexOf(item) == pos;
   }
  )
  return uniq
}

function getMethodsDups(obj) {
  let myFunctions = Object.getOwnPropertyNames(obj).filter(item => typeof obj[item] === 'function')
  let p = Object.getPrototypeOf(obj)
  return p ? myFunctions.concat(getMethodsDups(p)) : myFunctions
}

// describe an object or value and differentiate various important MarkLogic objects that log or render the same
function describe(x) {
  if (["string", "number", "boolean"].includes(typeof x))
    return typeof x
  if (Array.isArray(x)) {
    if (x.length == 0)
      return "Array (empty)"
    else 
      return "Array(item[0]: "+describe(x[0])+")"
  }
  let methods = getMethods(x) 
  if (methods.includes("toObject") && methods.includes("toJSON") && x.nodeKind ) {
    return "Node: " + x.nodeKind
  }
  else if (methods.length==11 && methods.includes("hasOwnProperty"))
    return "Regular Object" // regular JS object has 11 methods (note: so does a boolean)
  else if (methods.length==14 && methods.includes("toArray") && methods.includes("toJSON")) {
    if (fn.count(x)==0) 
      return "Sequence (empty)"
    else {
      let h = fn.head(x)
      return "Sequence(item 1: "+describe(fn.head(x))+ ")" // MarkLogic object representing an XPath sequence type
    }
  }
  else if (typeof x == "boolean") 
    return "xx"
}


// TEST ////

  let c = {foo: "foooo", bars: [{bar1:"b1"}, {bar2:2}, "b3"]}
  const builder = new NodeBuilder()
  builder.startDocument()
  builder.addNode(c) // maybe the map of sequences is converted when added as a node
  builder.endDocument()
  var newDocument = builder.toNode()
  let f = newDocument.xpath("/foo")
  let bs = newDocument.xpath("/bars")
  
let s = new Sequence([true, 2, "apple"])

let m = xdmp.xqueryEval("let $m := map:map() let $_ := map:put($m, 'foo', 'foooo') return $m")
result = [
describe("apple"),
describe(["apple"]),
describe(1),
describe(false),
describe(newDocument),
describe(s),
describe(m),
describe(c),
describe(f),
describe(bs),
  ]
result