Is key-value pair available in Typescript?

Yes. Called an index signature:

interface Foo {
   [key: string]: number;
}


let foo:Foo = {};
foo['hello'] = 123;
foo = {
  'leet': 1337
};
console.log(foo['leet']); // 1337

Here keys are string and values are number.

More

You can use an es6 Map for proper dictionaries, polyfilled by core-js.