embark/site/source/docs/smart_contract_objects.md
Michael Bradley, Jr 030fb4acc6 build(deps): bump web3[-*] from 1.2.4 to 1.2.6
Remove `bignumber.js` workaround (in the root, from PR #2152) because it's no
longer needed (verified locally).

Remove the `"skipLibCheck"` workaround (in `packages/plugins/solidity-tests`,
from PR #2152) because it's no longer needed (verified locally).

Refactor a typing in `packages/plugins/geth`. What's happening is that in web3
v1.2.4 `sendTransaction` has a return type of `PromiEvent<TransactionReceipt>`
but in v1.2.6 it has a return type of `PromiEvent<TransactionReceipt |
TransactionRevertInstructionError>`.

Compare:
* [v1.2.4/packages/web3-eth/types/index.d.ts#L291-L294](https://github.com/ethereum/web3.js/blob/v1.2.4/packages/web3-eth/types/index.d.ts#L291-L294)
* [v1.2.6/packages/web3-eth/types/index.d.ts#L295-L298](https://github.com/ethereum/web3.js/blob/v1.2.6/packages/web3-eth/types/index.d.ts#L295-L298)

The problem is that the `TransactionRevertInstructionError` type doesn't have a
`transactionHash` property. Since at present the code in
`packages/plugins/geth/src/devtxs.ts` only deals with the success case re:
`sendTransaction`, import the `TransactionReceipt` type from `web3-eth` and
cast the resolved return value's type using TypeScript's `as` operator.
2020-02-03 10:17:07 -06:00

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Markdown

title: Smart Contract Objects
layout: docs
---
### Interacting with contracts in Javascript
Embark will automatically take care of deployment for you and set all needed JS bindings. For example, the contract below:
```
// app/contracts/simple_storage.sol
contract SimpleStorage {
uint public storedData;
function SimpleStorage(uint initialValue) {
storedData = initialValue;
}
function set(uint x) {
storedData = x;
}
function get() constant returns (uint retVal) {
return storedData;
}
}
```
Will automatically be available in Javascript as:
```
// app/js/index.js
import SimpleStorage from 'Embark/contracts/SimpleStorage';
SimpleStorage.methods.set(100).send();
SimpleStorage.methods.get().call().then(function(value) { console.log(value) });
SimpleStorage.methods.storedData().call().then(function(value) { console.log(value) });
```
The syntax used is <a href="https://web3js.readthedocs.io/en/v1.2.6/" target="_blank">web3.js 1.2.6</a>