Move code samples to language folders consistently

content/_code-samples/address_encoding/js/encode_address.js

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+'use strict';
+const assert = require('assert');
+const crypto = require('crypto');
+const R_B58_DICT = 'rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz';
+const base58 = require('base-x')(R_B58_DICT);
+
+assert(crypto.getHashes().includes('sha256'));
+assert(crypto.getHashes().includes('ripemd160'));
+
+// Start with a public key. secp256k1 keys should be 33 bytes;
+//    Ed25519 keys should be 32 bytes prefixed with 0xED (a total of 33 bytes).
+
+// Ed25519 key:
+const pubkey_hex =
+  'ED9434799226374926EDA3B54B1B461B4ABF7237962EAE18528FEA67595397FA32';
+//// secp256k1 key:
+// const pubkey_hex =
+//   '0303E20EC6B4A39A629815AE02C0A1393B9225E3B890CAE45B59F42FA29BE9668D';
+
+const pubkey = Buffer.from(pubkey_hex, 'hex');
+assert(pubkey.length == 33);
+
+// Calculate the RIPEMD160 hash of the SHA-256 hash of the public key
+//   This is the "Account ID"
+const pubkey_inner_hash = crypto.createHash('sha256').update(pubkey);
+const pubkey_outer_hash = crypto.createHash('ripemd160');
+pubkey_outer_hash.update(pubkey_inner_hash.digest());
+const account_id = pubkey_outer_hash.digest();
+
+// Prefix the Account ID with the type prefix for an XRPL Classic Address, then
+//   calculate a checksum as the first 4 bytes of the SHA-256 of the SHA-256
+//   of the Account ID
+const address_type_prefix = Buffer.from([0x00]);
+const payload = Buffer.concat([address_type_prefix, account_id]);
+const chksum_hash1 = crypto.createHash('sha256').update(payload).digest();
+const chksum_hash2 = crypto.createHash('sha256').update(chksum_hash1).digest();
+const checksum =  chksum_hash2.slice(0,4);
+
+// Concatenate the address type prefix, the payload, and the checksum.
+// Base-58 encode the encoded value to get the address.
+const dataToEncode = Buffer.concat([payload, checksum]);
+const address = base58.encode(dataToEncode);
+console.log(address);
+// rnBFvgZphmN39GWzUJeUitaP22Fr9be75H (secp256k1 example)
+// rDTXLQ7ZKZVKz33zJbHjgVShjsBnqMBhmN (Ed25519 example)