let foo = 'foo';
// let foo: string

let foo = 'foo' as const;
// let foo: 'foo'

let foo = 7;
// let foo: number

let foo = 7 as const;
// let foo: 7;

객체

const myObject = {

    foo: 'bar',

    baz: 7,

};
/*
    const myObject: {

    foo: string;

    baz: number;

}
*/

const myObject = {

    foo: 'bar',

    baz: 7,

} as const;
/*
    const myObject: {

        readonly foo: "bar";

        readonly baz: 7;

    }
*/