You can do this a couple of ways.
The most simple, understandlbe way is to use the that
variable:
var that;
$('#' + this.ID + ' .selMake').on('change', that.getCarModel); // This will execute the function this.getcarModel
You can also use the bind
method in browsers that support ES5.
$('#' + this.ID + ' .selMake').on('change', this.getCarModel.bind(this));
If you're using underscore you might want to use its _.bind
function in order to make it cross-browser compatible:
$('#' + this.ID + ' .selMake').on('change', _.bind(this.getCarModel. this));