CODEWITHSUNDEEP
typescript
Carlos Garces
Carlos Garces

Reputation: 833

Cast map value on TypeScript

I'm very confused about how Map entries are managed on TypeScript

Consider the following code:

const foo = new Map();
foo.set(1, "1");
console.log('foo=', foo);
const myValue = foo.get(1) as number;
console.log('foo as number %i ', myValue );
console.log('foo as string %s ', myValue );

Gives me NaN with %i and works fine with %s

Change the code to

const myValue = +foo.get(1);

Works for me but looks like a ugly workaround.

What is the correct way to parse a get() on a Map object?

Upvotes: 0

Views: 1257

Answers (1)

captain-yossarian from Ukraine
captain-yossarian from Ukraine

Reputation: 33061

Just use generics and parseInt:


type StirngNumber<T extends number>=`${T}`
const foo = new Map<number, StirngNumber<number>>();
foo.set(1, "1");
const val = foo.get(1)
const myValue = val ? parseInt(val, 10) : 'can find a value' // string | undefined
console.log(myValue);

Upvotes: 1

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