Question

In the code below:

DbModels.prototype.updateById = function(_collection, id, field, value, callback) {
    this.getCollection(_collection, function(error, sel_collection) {
      if( error ) callback(error)
      else {
        sel_collection.update({_id: ObjectID.createFromHexString(id)}, {$set: {$[field].value:value}}, function(error, updated) {
          if( error ) callback(error)
          else callback(null, updated);
        });
      }
    });
};

I would like to use the value of the variable field as the name of the variable in $set. I tried using the following code $[field].value (as you can see in the code above), which doesn’t work. Any suggestions how to solve this?

Thanks!

Answer 1

There’s not such syntax in javascript as php ${$var_name};

One can use this[var_name] or window[var_name] (for global vars in browsers), but there’s no way to get local variable in current scope except eval, which is definitely considered bad.

Consider using a hash (object) for variable “scoping/namespacing”.