Create Object at Runtime

Question

I have a simple factory below that I would like to simplify and not be required to modify each time I add a new object that I would like to return. In Javascript, how would I be able to create an object at runtime? Thanks

switch (leagueId) {
  case 'NCAAF' :
      return new NCAAFScoreGrid();
  case 'MLB' :
      return new MLBScoreGrid();
  ... 
}

Answer 1

you can use eval method for example,

return eval("new "+leagueId+"ScoreGrid();");

eval will evaluate code at runtime and will return the object.

Answer 2

var leagues = {
    'NCAAF': NCAAFScoreGrid,
    'MLB':   MLBScoreGrid,
    // ...
};  // maybe hoist this dictionary out to somewhere shared

if (leagues[leagueId]) {
    return new leagues[leagueId]();
}
// else leagueId unknown

Answer 3

You can use the bracket operator to look-up the constructor.

new (window[leagueId + 'ScoreGrid'])(...);