TypeScript Objects as Dictionary types as in C#

arrays object dictionary typescript
Robert Taylor picture Robert Taylor · Nov 29, 2012 · Viewed 274.5k times · Source

I have some JavaScript code that uses objects as dictionaries; for example a 'person' object will hold a some personal details keyed off the email address.

var people = {<email> : <'some personal data'>};

adding   > "people[<email>] = <data>;" 
getting  > "var data = people[<email>];" 
deleting > "delete people[<email>];"

Is it possible to describe this in Typescript? or do I have to use an Array?

Answer

Ryan Cavanaugh picture Ryan Cavanaugh · Nov 29, 2012

In newer versions of typescript you can use:

type Customers = Record<string, Customer>

In older versions you can use:

var map: { [email: string]: Customer; } = { };
map['[email protected]'] = new Customer(); // OK
map[14] = new Customer(); // Not OK, 14 is not a string
map['[email protected]'] = 'x'; // Not OK, 'x' is not a customer

You can also make an interface if you don't want to type that whole type annotation out every time:

interface StringToCustomerMap {
    [email: string]: Customer;
}

var map: StringToCustomerMap = { };
// Equivalent to first line of above

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