Pushing items onto Array

How do you push items onto an array? The following throws an exception.

function ReadAllCribs() {
    var AllCribs = {};
    Project.Variables.Cribs.Reset();
    for (; !Project.Variables.Cribs.IsEOF()  {
        AllCribs.push(Project.Variables.Cribs.Value("CribNumber")); //<<< Exception

        Project.Variables.Cribs.Next();
    }