Dereference Object Property Path From String (v4)

Revision 4 of this benchmark created on May 20, 2015

Setup

function index(obj, i) {
    return obj[i]
  }
  var obj = {
    a: {
      b: {
        x: 0
      }
    }
  };
  
  function deref(obj, s) {
    var i = 0;
    s = s.split('.');
    while (obj && i < s.length)
      obj = obj[s[i++]];
    return obj;
  }
  
  
  //I left this here out of deference to the OP, but it didn't return correct result when I tested it locally - KC
  function derefrecursive(obj, s, i) {
    if (i === undefined) i = 0;
    if (i < s.length) return derefrecursive(obj[s[i]], s, i + 1);
    return obj;
  }
  
  //Function constructor method -- optimized for repeatedly dereferencing the same path (memoizedLookupFunction). Performs slower than eval() if you aren't reusing the path (lookupFunction).
  function lookupFunction(obj, path) {
    var func = Function("obj", "return obj." + path + ";");
    return func(obj);
  }
  
  var derefFuncs = {};
  function memoizedLookupFunction(obj, path) {
    if (!derefFuncs[path]) { 
      derefFuncs[path] = Function("obj", "return obj." + path + ";");
    }
    return derefFuncs[path](obj);
  }

Test runner

'a.b.x'.split('.').reduce(index, obj)

eval('obj.' + 'a.b.x')

deref(obj, 'a.b.x')

derefrecursive(obj, 'a.b.x'.split("."))

lookupFunction(obj, 'a.b.x')

memoizedLookupFunction(obj, 'a.b.x')

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

• Revision 1: published by James Wilkins on October 30, 2013
• Revision 2: published by Drew Noakes on February 27, 2014
• Revision 3: published by Stefan on February 13, 2015
• Revision 4: published on May 20, 2015