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I wrote the following code as a way of plucking data from a n-depth JavaScript object. It works a charm and even appends the parents of the the found item.

I was just wondering if you guys had any ideas on making it better.

//#region function recursiveFind
function recursiveFind(data, key, childKey, match, result) {

    ///<summary>Returns JS obj and its parents based on a data set, key and match.</summary>
    ///<param name="data" type="Object" optional="false">the data object you want to find within</param>
    ///<param name="key" type="String" optional="false">the key for the data you want to match against eg. 'id' will look for data.id</param>
    ///<param name="childKey" type="String" optional="false">the data object you want to find within</param>
    ///<param name="match" type="Any" optional="false">the value you wish to search for</param>
    ///<returns type="Object">returns the found result</returns>

    var parents = [];
    var depth = 0;
    var recurse = function (data, key, childKey, match, result) {
        // Build Parents
        depth++;

        // Check this Object
        if (data[key] === match) {
            result = data;
        }
        else if (depth === 1) {
            parents.push(data);

        }

        // If not found check children
        if (result === undefined) {
            if (data[childKey]) {
                $.each(data[childKey], function (k, v) {
                    if (v[key] === match) {
                        result = v;
                        return false;
                    } else {
                        result = recurse(v, key, childKey, match, result);
                        if (result) {
                            parents.push(v);
                            return false;
                        }
                    }
                });
            }
        }

        // Set parents object into the result
        if (result) {
            result.parents = $.extend([], parents);
        }

        // Clean up parents object
        depth--;
        if (depth === 0) {
            parents.length = 0;
        }
        return result;
    };
    return recurse(data, key, childKey, match, result);
}
//#endregion
\$\endgroup\$
  • \$\begingroup\$ You you add an example of use? \$\endgroup\$ – plalx Oct 11 '13 at 20:13
  • \$\begingroup\$ Are you sure ` parents.length = 0;` works? \$\endgroup\$ – konijn Dec 16 '13 at 19:52
  • \$\begingroup\$ @tomdemuyt yep, it is the preferred way of reseting an array in JavaScript stackoverflow.com/questions/1232040/… \$\endgroup\$ – Blowsie Dec 17 '13 at 10:58
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Overal

I think the code looks too busy just to find a key/value match in an object tree-structure, it took a while to figure out which part(s) bothered me.

Doing it twice

You are doing the matching twice, once with (data[key] === match) and once with (v[key] === match), it would be cleaner to leave the second check to recursion.

Function in a function

I am assuming you use a function in a function to keep track of depth and parents, which isn't worth it. You can do this in a single function with an optional parameter.

Naming

  • match -> matchValue because match sounds like a boolean to me
  • childKey - childrenKey because the key really points to an array
  • result.parents -> avoid this, what if the object already has a property called parents ?

Counter proposal

If you think about it, result can be considered the parent of key, so I would build a function that returns all parents in an array, if you wish you can then have recursiveFind call that.

function findParents( data, key, matchValue, childrenKey, parents )
{
  var i , children , childrenCount;
  /* Prevent the need for an inner function by re-passing parents */
  parents = parents || [];
  parents.push( data )
  /* Return immediately if we find a match */
  if( data[key] === matchValue )
    return parents.reverse(); 
  /* Are there children to inspect ? */
  if( !data[childrenKey] || !data[childrenKey].length )
    return false;
  children = data[childrenKey];
  childrenCount = children.length;
  /* See if any children have it ? */
  for( i = 0 ; i < childrenCount ; i++ )
  {
    if( parents = findParents( children[i] , key , matchValue , childrenKey , parents.slice() ) )
      return parents;
  }
  /* Fail.. */
  return false;
}

Then recursiveFind becomes

function recursiveFind(data, key, childrenKey, match )
{
  var parents = findParents( data , key, match ),
      result = parents.shift()
  result.parents = parents;
  return result;
}
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