Recursive Javascript

Question

Given a data structure as follows:

var endpoints = {
    // top level
    "orders": {
        url: "/orders",
        // child
        "sub-level": {
            url: "/sublevel"
        }
    },
    // users
    "users": {
        url: "/users",
        // child
        "another-sublevel": {
            url: "/another-sublevel"
        }
    }
}

How could I recurse over this generating a "Route" object each time I encounter a URL? I also need to track the parents to a route, so:

var Route = function(name, url, parents) {
}

Where name is the key (e.g. "orders" or "users" in the top level) url is obvious and "parents" is some sort of stack that's generated as we drill down each level.

I've had a couple of goes at writing this and I'm running into trouble with variable scope / passing attributes by reference vs. value and all sorts of other weirdness.

The data structure is not fixed either, but needs to contain that information.

Mic · Accepted Answer · 2011-05-19 07:21:02Z

1

Here's an example

   function recurse(obj, parents){
        var prop;
        parents = parents || [];
        for(prop in obj){
            if(typeof(obj[prop]) === 'string' && prop === 'url'){
                //do something with url
                console.log(obj[prop], parents.join('->'));
            }else{
                parents.push(prop);
                recurse(obj[prop], parents);
                parents = [];
            }
        }
    }

    recurse(endpoints);

edited May 19, 2011 at 7:21

answered May 19, 2011 at 7:13

Mic

25.2k9 gold badges61 silver badges71 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Samuel Over a year ago

Thanks, will test on Monday then award answer!

Rudie Over a year ago

(Using === with typeof is not necessary.)

Rudie Over a year ago

WHy it's NOT necessary? Because the result of typeof is ALWAYS a string, so there's no need to type check... === is good, but it's not always necessary. Somewhere on here is why it's good to not ALWAYS use ===.

Mic Over a year ago

What is the advantage of == ? I thought === doesn't make any conversions, while == makes it.

gnab · Accepted Answer · 2011-05-19 08:00:54Z

0

The following code will map the data structure into a list of Route objects, each containing the belonging name, url and list of parents:

function mapRoutes(endpoints, parents, routes) {
  var name, url;

  for (name in endpoints) {
    if (!endpoints.hasOwnProperty(name) || name === 'url') {
      continue;
    }   

    url = endpoints[name]['url'];

    routes.push(new Route(name, url, parents));

    mapRoutes(endpoints[name], parents.concat([name]), routes);
  }

  return routes;
}

var routes = mapRoutes(endpoints, [], []);

answered May 19, 2011 at 8:00

gnab

9,6011 gold badge23 silver badges13 bronze badges

1 Comment

Samuel Over a year ago

Thanks, will test this answer and the other one on Monday and award to the most elegant :)

Collectives™ on Stack Overflow

Recursive Javascript

2 Answers 2

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related