# Provider object: 🔌 connect to the network :

The first thing to do: define with which network you want to interact. With the Provider object, you define the network to use :

`import {Provider} from 'starknet';`

## Connect your DAPP to Starknet testnet 1 & 2 :

`const provider = new Provider({ sequencer: { network: 'goerli-alpha' } }) // for testnet 1
const provider = new Provider({ sequencer: { network: 'goerli-alpha-2' } })  // for testnet 2`

Newton

How do I connect my DAPP to Starknet testnet using starknetjs?

following this page from the docs https://starknet.io/docs/hello_starknet/intro.html
I copied the code, compiled it using starknet compile, and when I go to declare it using starknet declare Im getting 
Status code: 500; text: {"code": "StarknetErrorCode.ENTRY_POINT_NOT_FOUND_IN_CONTRACT", "message": "Entry point <address>caed693fa4008dcdb4963b3 not found in contract with class hash <address>975148f6af3e9abddfdc701."}
Any help would be appreciated.

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

StarknetErrorCode.ENTRY_POINT_NOT_FOUND_IN_CONTRACT error in Cairo. Can anyone help?

Hi everyone, I have a technical question:

We know that L2s are taking transaction load off of the Ethereum, but how is that process taking place? Is there a threshold of optimum transaction speed/cost? Are L2s only intervening when the L1 is congested or that threshold is passed?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

 Is there a threshold of optimum transaction speed/cost in L2s?

该从该从哪里哪里开始开始学起学起呢呢？？PythonPython嘛嘛？？


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/479)_

开始学习Cairo

### *From Newton AI*
*"Assembly" is a low-level language that is used to write smart contracts for the Ethereum Virtual Machine (EVM). It is similar to machine code, which is the code that is run directly on a computer's central processing unit (CPU). Assembly is often used in Solidity contracts to perform complex tasks or to optimize the performance of the contract.*

*If a Solidity contract contains assembly code, it is important to be careful when working with it, as it can be difficult to read and understand. Additionally, certain assembly instructions, known as "special EVM calls," can have unintended consequences if not used correctly. For example, some special EVM calls can cause a contract to consume an excessive amount of gas, which can make it more expensive for users to interact with the contract.*

*It is generally recommended to avoid using assembly in Solidity contracts if possible, as it can make the contract more difficult to understand and maintain. If you do need to use assembly, it is important to thoroughly test and debug the contract to ensure that it functions as intended.*

What if my solidity contract contains Assembly or special EVM calls ?

Hello! This is day 17 of the 17 days of the Cairo Challenge. In this challenge I want to ask you [install](https://www.cairo-lang.org/docs/quickstart.html) Cairo and try to launch your first program. What have you implemented as your first Cairo language program?

**Step 1**
```solidity
// 1. Make sure that you installed dev packages on your device
sudo apt install -y libgmp3-dev // Linux
brew install gmp // Mac OS
```
**Step 2**
```solidity
// 2. Install Cairo using Python virtual environment
python3.9 -m venv ~/cairo_venv
source ~/cairo_venv/bin/activate
pip3 install ecdsa fastecdsa sympy;
pip3 install cairo-lang;
```
**Step 3**
```bash
// 3. Make sure you have python 3.9. Because Cairo was tested with python3.9. To make it work with python3.6, you will have to install contextvars:
pip3 install contextvars
```
**Step 4**
```python
// 4. Write your program
// Create a file, named hello.cairo, with the following lines:
 
func main() {
		// edit me: you can add here any output, best program wins the challenge
    ret;
}

```solidity
//5. Compile your program
cairo-compile hello.cairo --output hello_compiled.json
```
**Last step**
```solidity

//6. Run:
cairo-run \
  --program=hello_compiled.json --print_output \
  --print_info --relocate_prints

//7. Debug:
//You can open the Cairo tracer by providing the --tracer flag to cairo-run. Then open it at http://localhost:8100/.
```
If you have questions, create them on Newton and we will help!

---
> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

How to install Cairo v0.10.0 on my device?

hey guys - is there a cheatsheet somewhere will all the most usefull commands? Check logs, check latest version etc?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Is there a cheatsheet somewhere will all the most usefull commands

When running my python tests I get:


 NotImplementedError: Invoking through an account contract is not supported yet, please use execute() instead.


 Has anyone seen this problem and know of a solution?


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/1179)_

Popular tags

How do I connect my DAPP to Starknet testnet using starknetjs?

1 answers

Provider object: 🔌 connect to the network :

Connect your DAPP to Starknet testnet 1 & 2 :

Your answer

Related

You may find useful