Question

I’m currently using javascript eval() to check and create a multidimensional object that I have no idea of the depth.

Basically, I want to know if there’s any way to create this multi-depth object. The object can be as deep as result['one']['two']['three']['four']['five']['six']['seven']. I know there are cases where using eval() is perfectly fine, but I’m also worried about performance. I thought about referencing each depth to a new variable, but I don’t know how to do pointers in Javascript

      create = function(fields, create_array){
        var field;

        for (j = 0; j < len; j++){
          field = fields.slice(0, j).join('');
          if (field){
            // is there any way to do this without eval?
            eval('if (typeof result' + field + ' == "undefined" || !result' + field + ') result' + field + ' = ' + (create_array?'[]':'{}') + ';');
          }
        }
      }

Answer 1

Never mind, found my way in. I used a recursive function to ensure that the object was created properly.

      create = function(create_array, res, path){
        var field = fields.shift();

        if (field){ 
          if (typeof res[field] == "undefined" || !res[field]) res[field] = (create_array?[]:{});
          path.push('["' + field + '"]');
          create(create_array, res[field], path);
        }
      }

      var result = {}, strpath = [], fields[];
      create(true, result, strpath);
      eval('result' + strpath.join('') + ' = value;');

being variable “field” a variable outside the function, that contained the levels of the object. doing result["field"]["name"]["first"] = value without the ["field"] or ["name"] field existing or defined as an object, would throw an error and stop execution, that’s why I’m pre-creating the object variable, either as an array or object.

I couldn’t find another option for the second eval() though. There’s no way to provide a way to access multiple properties on an object without knowing the depth.