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Overview

The JavaScript Stellar SDK facilitates integration with the Stellar Horizon API server and submission of Stellar transactions, either on Node.js or in the browser. It has two main uses: querying Horizon and building, signing, and submitting transactions to the Stellar network.

Building and installing js-stellar-sdk
Examples of using js-stellar-sdk

Querying Horizon

js-stellar-sdk gives you access to all the endpoints exposed by Horizon.

Building requests

js-stellar-sdk uses the Builder pattern to create the requests to send to Horizon. Starting with a server object, you can chain methods together to generate a query. (See the Horizon reference documentation for what methods are possible.)

var StellarSdk = require('stellar-sdk');
var server = new StellarSdk.Server('https://horizon-testnet.stellar.org');
// get a list of transactions that occurred in ledger 1400
server.transactions()
    .forLedger(1400)
    .call().then(function(r){ console.log(r); });

// get a list of transactions submitted by a particular account
server.transactions()
    .forAccount('GASOCNHNNLYFNMDJYQ3XFMI7BYHIOCFW3GJEOWRPEGK2TDPGTG2E5EDW')
    .call().then(function(r){ console.log(r); });

Once the request is built, it can be invoked with .call() or with .stream(). call() will return a promise to the response given by Horizon.

Streaming requests

Many requests can be invoked with stream(). Instead of returning a promise like call() does, .stream() will return an EventSource. Horizon will start sending responses from either the beginning of time or from the point specified with .cursor(). (See the Horizon reference documentation to learn which endpoints support streaming.)

For example, to log instances of transactions from a particular account:

var StellarSdk = require('stellar-sdk')
var server = new StellarSdk.Server('https://horizon-testnet.stellar.org');
var lastCursor=0; // or load where you left off

var txHandler = function (txResponse) {
    console.log(txResponse);
};

var es = server.transactions()
    .forAccount(accountAddress)
    .cursor(lastCursor)
    .stream({
        onmessage: txHandler
    })

Handling responses

XDR

The transaction endpoints will return some fields in raw XDR form. You can convert this XDR to JSON using the .fromXDR() method.

An example of re-writing the txHandler from above to print the XDR fields as JSON:

var txHandler = function (txResponse) {
    console.log( JSON.stringify(StellarSdk.xdr.TransactionEnvelope.fromXDR(txResponse.envelope_xdr, 'base64')) );
    console.log( JSON.stringify(StellarSdk.xdr.TransactionResult.fromXDR(txResponse.result_xdr, 'base64')) );
    console.log( JSON.stringify(StellarSdk.xdr.TransactionMeta.fromXDR(txResponse.result_meta_xdr, 'base64')) );
};

Following links

The links returned with the Horizon response are converted into functions you can call on the returned object. This allows you to simply use .next() to page through results. It also makes fetching additional info, as in the following example, easy:

server.payments()
    .limit(1)
    .call()
    .then(function(response){
        // will follow the transactions link returned by Horizon
        response.records[0].transaction().then(function(txs){
            console.log(txs);
        });
    });

Transactions

Building transactions

See the Building Transactions guide for information about assembling a transaction.

Submitting transactions

Once you have built your transaction, you can submit it to the Stellar network with Server.submitTransaction().

const StellarSdk = require('stellar-sdk')
StellarSdk.Network.useTestNetwork();
const server = new StellarSdk.Server('https://horizon-testnet.stellar.org');

(async function main() {
    const account = await server.loadAccount(publicKey);

    /* 
        Right now, we have one function that fetches the base fee.
        In the future, we'll have functions that are smarter about suggesting fees,
        e.g.: `fetchCheapFee`, `fetchAverageFee`, `fetchPriorityFee`, etc.
    */
    const fee = await server.fetchBaseFee();

    const transaction = new StellarSdk.TransactionBuilder(account, { fee })
        .addOperation(
            // this operation funds the new account with XLM
            StellarSdk.Operation.payment({
                destination: "GASOCNHNNLYFNMDJYQ3XFMI7BYHIOCFW3GJEOWRPEGK2TDPGTG2E5EDW",
                asset: StellarSdk.Asset.native(),
                amount: "20000000"
            })
        )
        .setTimeout(30)
        .build();

    // sign the transaction
    transaction.sign(StellarSdk.Keypair.fromSecret(secretString)); 

    try {
        const transactionResult = await server.submitTransaction(transaction);
        console.log(transactionResult);
    } catch (err) {
        console.error(err);
    }
})()
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