Use `unknown` with typechecks and avoid `as`

unknown.ts

function test(p: unknown | unknown[]) {
    /** Wrong */
    if (p as unknown as string[]) {
        console.log('p isn\'t string, but executed', p);
        /** p is not type safe here, we have to use as everytime */
        p as unknown as string[]
    }

    /** Better */
    if (Array.isArray(p) && typeof p[0] === 'string') {
        const z0 = p[0]; // p[0] is inferred as string
        try{
        const z1 = p[1]; // p[1] is inferred as any, might throw error of element doesn't exist
        } catch(e){
            console.error(e)
        }
    } else {
        throw 'Invalid data, should be string array';
    }

    /** Not the best, But safe (suggest me best) */
    if (Array.isArray(p) && p.every(a => typeof a === 'string')) {
        const newArr: string[] = p; // Here p is any[], but after assignment It is type safe and we have already tested it is string

        const z0 = p[0]; // p[0] is inferred as any
        const n0 = newArr[0]; // p[0] is inferred as any
        
        // We could also check length of array
        try{
            const z1 = p[1]; // p[1] is inferred as any // might throw error of element doesn't exist
            const n1 = newArr[1]; // p[1] is inferred as any // might throw error of element doesn't exist
        }catch(e){
            console.error(e);
        }
    } else {
        throw 'Invalid data, should be string array';
    }

}


// test({});
// test('Hello');
// test(['Hello', {}]);
test(['Hello']);
test(['Hello', 'HI' ]);