# Node.js to/from candid **URL:** \ **Category:** Developers\ **Tags:** candid, agent\ **Created:** [April 20, 2023, 11:33am UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526 "2023-04-20T11:33:01Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![ZenVoich](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/zenvoich/32/5969_2.png) [@ZenVoich](https://forum.dfinity.org/u/ZenVoich)\ **Post date:** [April 20, 2023, 11:33am UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/1 "2023-04-20T11:33:01Z")
I want to backup/restore canister data using agent.js. Also I want to parse/generate `.did` file with canister init args. Is there way to parse candid data based on idlFactory? Is there way to convert js data fetched via agent.js to candid textual or binary format? ---
**Author:** ![anon74414410](https://avatars.discourse-cdn.com/v4/letter/a/85f322/32.png) [@anon74414410](https://forum.dfinity.org/u/anon74414410)\ **Post date:** [April 20, 2023, 2:30pm UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/2 "2023-04-20T14:30:12Z")
You have a few options. @infu was sharing on Discord about a JS parser they’ve been writing from scratch in the Discord channel. We have some tools, like [ic0 - npm](https://www.npmjs.com/package/ic0) and [@infu/icblast - npm](https://www.npmjs.com/package/@infu/icblast) which currently compile the `didc` tool to run in webassembly, and they also have some simplified interfaces for making calls to those canisters after the fact. If you want to stick with `agent-js`, here is a little snippet that makes a call to the Candid UI canister to do the conversion from `did` for you. This is how Candid UI and the [Candid UI web component](https://github.com/dfinity/dfn-components/tree/main/packages/candid-ui) parse did files into JS > ---
**Author:** ![infu](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/infu/32/11321_2.png) [@infu](https://forum.dfinity.org/u/infu)\ **Post date:** [April 20, 2023, 4:09pm UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/3 "2023-04-20T16:09:18Z")
Here is the .did parsing repo > **[GitHub - vvv-interactive/candid-js](https://github.com/vvv-interactive/candid-js)** > > Contribute to vvv-interactive/candid-js development by creating an account on GitHub. ---
**Author:** ![ZenVoich](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/zenvoich/32/5969_2.png) [@ZenVoich](https://forum.dfinity.org/u/ZenVoich)\ **Post date:** [April 21, 2023, 8:51am UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/4 "2023-04-21T08:51:16Z")
> [@infu](#): > > Here is the .did parsing repo > > [GitHub - vvv-interactive/candid-js](https://github.com/vvv-interactive/candid-js) Unfortunately, it does not work with values, e.g. `record { name = "A"; };` ---
**Author:** ![ZenVoich](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/zenvoich/32/5969_2.png) [@ZenVoich](https://forum.dfinity.org/u/ZenVoich)\ **Post date:** [April 21, 2023, 8:54am UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/5 "2023-04-21T08:54:18Z")
> [@anon74414410](#): > > If you want to stick with `agent-js`, here is a little snippet that makes a call to the Candid UI canister to do the conversion from `did` for you. This is how Candid UI and the [Candid UI web component](https://github.com/dfinity/dfn-components/tree/main/packages/candid-ui) parse did files into JS Always returns `undefined` no matter what data I send (even invalid ones) ---
**Author:** ![infu](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/infu/32/11321_2.png) [@infu](https://forum.dfinity.org/u/infu)\ **Post date:** [April 21, 2023, 9:15am UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/6 "2023-04-21T09:15:15Z")
Can you throw here what you are trying to parse ---
**Author:** ![ZenVoich](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/zenvoich/32/5969_2.png) [@ZenVoich](https://forum.dfinity.org/u/ZenVoich)\ **Post date:** [April 21, 2023, 11:29am UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/7 "2023-04-21T11:29:22Z")
initArgs.did: ```auto record { name = "A"; }; ``` Run `npx candid-js@latest initArgs.did json` ```auto /home/zen/.npm/_npx/959bee5921d90e41/node_modules/candid-js/src/index.js:29 throw parser.errors; ^ [ NotAllInputParsedException: Redundant input, expecting EOF but found: record at RecognizerEngine.ruleFinallyStateUpdate (/home/zen/.npm/_npx/959bee5921d90e41/node_modules/chevrotain/lib/src/parse/parser/traits/recognizer_engine.js:439:29) at CandidParser.invokeRuleWithTry [as candid] (/home/zen/.npm/_npx/959bee5921d90e41/node_modules/chevrotain/lib/src/parse/parser/traits/recognizer_engine.js:142:26) at transpile (/home/zen/.npm/_npx/959bee5921d90e41/node_modules/candid-js/src/index.js:27:20) at Object. (/home/zen/.npm/_npx/959bee5921d90e41/node_modules/candid-js/cli.js:17:16) at Module._compile (node:internal/modules/cjs/loader:1254:14) at Module._extensions..js (node:internal/modules/cjs/loader:1308:10) at Module.load (node:internal/modules/cjs/loader:1117:32) at Module._load (node:internal/modules/cjs/loader:958:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12) at node:internal/main/run_main_module:23:47 { token: { image: 'record', startOffset: 0, endOffset: 5, startLine: 1, endLine: 1, startColumn: 1, endColumn: 6, tokenTypeIdx: 4, tokenType: { name: 'Record', PATTERN: /\brecord\b/, tokenTypeIdx: 4, CATEGORIES: [], categoryMatches: [], categoryMatchesMap: {}, isParent: false } }, resyncedTokens: [], context: { ruleStack: [], ruleOccurrenceStack: [] } } ] Node.js v18.16.0 ``` Works with: ```plaintext type A = nat; ``` ---
**Author:** ![anon74414410](https://avatars.discourse-cdn.com/v4/letter/a/85f322/32.png) [@anon74414410](https://forum.dfinity.org/u/anon74414410)\ **Post date:** [April 21, 2023, 3:26pm UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/8 "2023-04-21T15:26:42Z")
Oh, the candid UI endpoint is for a full service. It’s not designed for partial translation of candid to JS. For example, this works: ```auto import { IDL } from "@dfinity/candid"; import fetch from "isomorphic-fetch"; import { Actor, HttpAgent } from "@dfinity/agent"; export const candidToJS = async (candid_source: string) => { // call didjs canister const didjs_interface: IDL.InterfaceFactory = ({ IDL }) => IDL.Service({ did_to_js: IDL.Func([IDL.Text], [IDL.Opt(IDL.Text)], ["query"]), }); const candidCanister = `a4gq6-oaaaa-aaaab-qaa4q-cai`; const agent = new HttpAgent({ host: "https://icp-api.io", fetch }); const didjs = Actor.createActor(didjs_interface, { agent, canisterId: candidCanister, }); const js: any = await didjs.did_to_js(candid_source); if (Array.isArray(js) && js.length === 0) { return undefined; } return js[0]; }; const str = `service : { whoami: () -> (principal) query; }` candidToJS(str).then(console.log) ``` ---
**Author:** ![infu](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/infu/32/11321_2.png) [@infu](https://forum.dfinity.org/u/infu)\ **Post date:** [April 21, 2023, 3:45pm UTC](https://forum.dfinity.org/t/node-js-to-from-candid/19526/9 "2023-04-21T15:45:19Z")
Candid is interface description language. What you want to parse isn’t valid Candid. It seems you are trying to parse data. Unless “A” is another type identifier, but then it should probably be record : { name : “A” } You can use - didc check file.did to see if its valid first. You can dl it from the Candid github repo. The only time you will need candid-js is probably if you are making IC browser. If you just want to encode with a spec, then the rest of the tools like agentjs will get it done Ok after reading your initial post, there is textual data format used in dfx for example, but I am not sure where the encoders for it are. To covert obj to binary using candid you can use IDL.encode(jsIdl, data) also there is IDL.decode. You have to take the jsIdl out of the idlFactory function