What is the best way to get/set an objects deep property in Javascript?

Question

It is notoriously annoying to get a deeper property from an object. If the parent does not exist, you get an error. So you need to stop getting to the property when a parent doe

Answer 1

Instead of try..catch, just test for the property:

function getProp(path, parent) {
    path = path.split('.');

    for (var k=0, kLen=path.length; k<kLen; k++) {

        if (parent.hasOwnProperty(path[k])) {
            parent = parent[path[k]];

        } else {
          return; // undefined? null? error?
        }
    }
    return parent;
}

var obj = {a: {b: {c: 'C', d:'D'}}};

console.log(
  getProp('a.b.d', obj)  // D
);      

Answer 2

Builtin ways, no. If you're in Node.js platform you can try some package like dotty.

Anyway, the way I think you could do it is somewhat like this (I haven't tested it! But I think it could work):

key.split( "." ).reduce(function( memo, part ) {
   if ( typeof memo !== "object" || memo[ part ] === undefined ) {
      return;
   }

   return memo[ part ];
}, obj );