Computed properties

Initializing an object with dynamic properties can be a bit of a burden. Take the following example:

type NeighborMap = { [name: string]: Node };
type Node = { name: string; neighbors: NeighborMap;}
function makeNode(name: string, initialNeighbor: Node): Node {
    var neighbors: NeighborMap = {};
    neighbors[initialNeighbor.name] = initialNeighbor;
    return { name: name, neighbors: neighbors };
}

Here we need to create a variable to hold on to the neighbor-map so that we can initialize it. With TypeScript 1.5, we can let the compiler do the heavy lifting:

function makeNode(name: string, initialNeighbor: Node): Node {
    return {
        name: name,
        neighbors: {
            [initialNeighbor.name]: initialNeighbor
        }
    }
}