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https://github.com/kilnfi/typescript-case-study
Typescript case study
https://github.com/kilnfi/typescript-case-study
Last synced: 7 days ago
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Typescript case study
- Host: GitHub
- URL: https://github.com/kilnfi/typescript-case-study
- Owner: kilnfi
- Created: 2024-02-14T13:36:48.000Z (12 months ago)
- Default Branch: main
- Last Pushed: 2024-03-10T15:44:50.000Z (11 months ago)
- Last Synced: 2024-04-14T01:55:22.103Z (10 months ago)
- Size: 2.93 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Typescript Case Study
Please send us your solution as a zip file or a link to a public git repository.
It should contain a succinct report explaining your solution and thought process.
# Exercise 1
Bootstrap a bun project using:
```bash
bun init -y
```
Create a function called `fetchBalance`.
```typescript
async function fetchBalance(address: `0x${string}`): Promise;
```
This function should fetch the balance of an Ethereum address and return a promise that resolves to the balance of the address in wei (bigint). You are not allowed to use **any** other library than the native Bun APIs.
You can use this Infura RPC endpoint: `https://mainnet.infura.io/v3/f1b70935143f4b22b3c165d6bdfd3021`
Your function should be able to batch requests and return the balance of multiple addresses in a single HTTP request.
For example this code should only do a single HTTP request:
```typescript
const addresses = [
"0xF7B31119c2682c88d88D455dBb9d5932c65Cf1bE",
"0x3CBdeD43EFdAf0FC77b9C55F6fC9988fCC9b757d",
"0x53b6936513e738f44FB50d2b9476730C0Ab3Bfc1",
"0x72a5843cc08275C8171E582972Aa4fDa8C397B2A",
"0x1da5821544e25c636c1417Ba96Ade4Cf6D2f9B5A",
] as const;
const balances = await Promise.all(addresses.map(fetchBalance));
```
and this example should only send 3 HTTP requests:
```typescript
const addresses = [
"0xF7B31119c2682c88d88D455dBb9d5932c65Cf1bE",
"0x3CBdeD43EFdAf0FC77b9C55F6fC9988fCC9b757d",
"0x53b6936513e738f44FB50d2b9476730C0Ab3Bfc1",
"0x72a5843cc08275C8171E582972Aa4fDa8C397B2A",
"0x1da5821544e25c636c1417Ba96Ade4Cf6D2f9B5A",
] as const;
const balances = await Promise.all(addresses.map(fetchBalance));
const balances_2 = await Promise.all(addresses.map(fetchBalance));
const balances_3 = await Promise.all([...addresses.map(fetchBalance), ...addresses.map(fetchBalance)]);
```
# Exercise 2
Provide a better and safer implementation of the following typescript native types:
Example with toLowerCase:
```typescript
const str = "HELLO";
const lowercase = str.toLowerCase(); // type of lowercase should be "hello" instead of string
````
```typescript
interface String {
/**
* Returns string lowercased
*/
toLowerCase(): string;
/**
* Returns true if searchString appears as a substring of the result of converting this
* object to a String, at one or more positions that are
* greater than or equal to position; otherwise, returns false.
*/
includes(searchString: string, position?: number): boolean;
/**
* Split a string into substrings using the specified separator and return them as an array.
*/
split(separator: string): string[];
/**
* Replaces text in a string, using a regular expression or search string.
*/
replace(searchValue: string, replaceValue: string): string;
/**
* Returns true if the sequence of elements of searchString converted to a String is the
* same as the corresponding elements of this object (converted to a String) starting at
* position. Otherwise returns false.
*/
startsWith(searchString: string, position?: number): boolean;
}
```