Question

I have a bunch of objects assigned to variables:

var ElectricCar = {
    start: function(){ alert('started electric car') }
};

var BioDieselCar = {
    start: function(){ alert('started bio diesel car') }
};

I want to call the start method on one of these objects, but I only have a string to work with:

var Starter = {
    init: function(carType){
        //... start the car that matches car type
    }
};

Starter.init('ElectricCar');

How can I call the start method on the appropriate object?

Answer 1

The preferred technique would require refactoring your code slightly.

var cars = {
    ElectricCar: {
        start: function(){ alert('started electric car') }
    },
    BioDieselCar: {
        start: function(){ alert('started bio diesel car') }
    }
};

var carType = 'ElectricCar';

// access the properties of cars by string
cars[carType].start();

This technique is preferable because it avoids the use of eval. By converting your vars to properties of an object, you can reference them by string.