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October 16, 2025 15:26
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Trivial function call ABI encoder/decoder online (Ethereum/Web3)
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| <!DOCTYPE html> | |
| <head> | |
| <script src="//cdnjs.cloudflare.com/ajax/libs/web3/1.6.0/web3.min.js" integrity="sha512-+BhnLgfzIDDjssoEWHPmdgWRvbwIEdj0Xfiys7uSqfQWpMEOJ4ymJ88O6B1cB0j+4zjb5GhO+sb/kEicggvUQQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script> | |
| </head> | |
| <h1>Encode eth_call using ABI</h1> | |
| ABI:<br> | |
| <textarea id="abiField" style="width: 100%; height: 10em;"> | |
| { | |
| "inputs": [ | |
| { | |
| "internalType": "uint256", | |
| "name": "", | |
| "type": "uint256" | |
| } | |
| ], | |
| "name": "proposals", | |
| "outputs": [ | |
| { | |
| "internalType": "bytes32", | |
| "name": "name", | |
| "type": "bytes32" | |
| }, | |
| { | |
| "internalType": "uint256", | |
| "name": "voteCount", | |
| "type": "uint256" | |
| } | |
| ], | |
| "stateMutability": "view", | |
| "type": "function" | |
| } | |
| </textarea> | |
| <input type="button" value="Evaluate ABI" onclick="evalAbi()"> | |
| <div id="methodParams"> | |
| </div> | |
| <input type="button" value="Encode call" onclick="encodeCall()"><br> | |
| <input type="button" value="Decode call" onclick="decodeCall()"><br> | |
| Encoded message:<br> | |
| <textarea id="outputField" style="width: 100%; height: 10em;"> | |
| </textarea> | |
| <script> | |
| var abi; | |
| function evalAbi() { | |
| console.log("parsing abi", abiField.value); | |
| abi = JSON.parse(abiField.value); | |
| methodParams.innerHTML = ''; | |
| var id = 0; | |
| abi.inputs.forEach(function(input){ | |
| methodParams.innerHTML += input.name + ': <input type="text" id="input'+id+'"> ('+input.type+')<br>'; | |
| id++; | |
| }); | |
| } | |
| function encodeCall() { | |
| var id = 0; | |
| var params = []; | |
| abi.inputs.forEach(function(input){ | |
| params.push(document.getElementById("input"+id).value); | |
| id++; | |
| }); | |
| console.log("encoding params", params); | |
| const web3 = new Web3(window.ethereum); | |
| var output = web3.eth.abi.encodeFunctionCall(abi, params); | |
| console.log("done", output); | |
| outputField.value = output; | |
| } | |
| function decodeCall() { | |
| evalAbi(); | |
| const paramsHexa = outputField.value.slice(10); // skip 0x and func signature | |
| const types = abi.inputs.map(i => i.type); | |
| const web3 = new Web3(window.ethereum); | |
| const params = web3.eth.abi.decodeParameters(types, paramsHexa); | |
| console.log('decoded params', params); | |
| var id = 0; | |
| abi.inputs.forEach(function(input){ | |
| document.getElementById("input"+id).value = params[id]; | |
| id++; | |
| }); | |
| } | |
| </script> |
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