Syntax

exchange.IO("encode", ...)

Encodes data using ABI encoding.


    
    
    
exchange.IO(k, dataFormat, ...args)


    
    
    
exchange.IO(k, address, dataFormat)


    
    
    
exchange.IO(k, address, dataFormat, ...args)

Examples

Encoding a call to the unwrapWETH9 method as an example.


    javascript
    
    
function main() {
    // ContractV3SwapRouterV2 mainnet address : 0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45
    // unwrapWETH9 is not an ERC20 method: register the ABI first (built-in template)
    var router = "0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45"
    exchange.IO("abi", router, "uniswapV3SwapRouter02")
    // 1 is amountMinimum, the minimum amount to unwrap, in wei (not 1 WETH): the router unwraps
    // all the WETH it holds into ETH and sends it to the recipient (the current wallet here);
    // the transaction fails if the amount is less than amountMinimum
    var data = exchange.IO("encode", router, "unwrapWETH9(uint256,address)", 1,
        exchange.IO("address"))
    Log(data)
    // Output: call data starting with 49404b7c (without 0x)
}

An encoding example equivalent to abi.encode in Solidity.


    javascript
    
    
function main() {
    var x = 10
    var address = "0x02a5fBb259d20A3Ad2Fdf9CCADeF86F6C1c1Ccc9"
    var str = "Hello World"
    var array = [1, 2, 3]
    // uint is equivalent to uint256; you can also write uint directly
    var ret = exchange.IO("encode", "uint256,address,string,uint256[]", x, address, str, array)
    Log("ret:", ret)
    // Output: ret is a hexadecimal string formed by concatenating the following 32-byte fields in order
    // 000000000000000000000000000000000000000000000000000000000000000a  x
    // 00000000000000000000000002a5fbb259d20a3ad2fdf9ccadef86f6c1c1ccc9  address
    // 0000000000000000000000000000000000000000000000000000000000000080  offset of str
    // 00000000000000000000000000000000000000000000000000000000000000c0  offset of array
    // 000000000000000000000000000000000000000000000000000000000000000b  length of str
    // 48656c6c6f20576f726c64000000000000000000000000000000000000000000  data of str
    // 0000000000000000000000000000000000000000000000000000000000000003  length of array
    // 0000000000000000000000000000000000000000000000000000000000000001  first element of array
    // 0000000000000000000000000000000000000000000000000000000000000002  second element of array
    // 0000000000000000000000000000000000000000000000000000000000000003  third element of array
}

Supports encoding tuples or type sequences that contain tuples. In this example the type sequence consists of tuple and bytes, so two more arguments must be passed when calling exchange.IO() to encode:
- 1. The variable corresponding to the tuple type:
```
            json
            
            
[30, 20, "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"]
```
  The tuple's values are passed by position as an array; the number, order and types of its elements must all match (uint256,uint8,address) in the types argument. A literal tuple has no field names; when decoded, the fields are named by position as Field1, Field2, and so on.
- 1. The variable corresponding to the bytes type:
```
            json
            
            
"0011"
```
```
    javascript
    
    
function main() {
    var types = "(uint256,uint8,address),bytes"
    var ret = exchange.IO("encode", types, [30, 20, "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"],
        "0011")
    Log("encode: ", ret)
}
```

Supports encoding arrays or type sequences that contain arrays.


    javascript
    
    
function main() {
    var path = ["0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
        "0xdac17f958d2ee523a2206206994597c13d831ec7"]   // ETH address, USDT address
    var ret = exchange.IO("encode", "address[]", path)
    Log("encode: ", ret)
}

Returns

Type	Description
string	The encoded data.

Arguments

Name	Type	Required	Description
k	string	Yes	Fixed as `encode`, indicating data encoding.
address	string	No	Smart contract address. When calling `exchange.IO("encode", ...)`, passing the `address` argument encodes a method call on the smart contract; if the `address` argument is not passed, the function encodes the data according to the specified type sequence, which is equivalent to `abi.encode` in `Solidity`.
dataFormat	string	Yes	The method, types and order of the data to be encoded.
arg	string / number / array / any	No	The specific data values matching the `dataFormat` argument. `arg` can be passed multiple times; their types and number are determined by the `dataFormat` argument. Tuples are passed as arrays.