eosjs-api/lib/exported-helpers.js

Application programming interface to EOS blockchain nodes.

'use strict';

module.exports = {

  // Under "api:" all functions must take api as their 1st parameter
  api: {
    createTransaction: createTransaction
  }

  /**
    @typedef {object} headers
    @property {number} ref_block_num - Last irreversible block number.  The
    bit-wise AND operation is used to keep this value with the size of a Uint16
    size (a block num in the last 2^16 blocks).  Example:
    `get_info.last_irreversible_block_num & 0xFFFF`
  
    @property {number} ref_block_prefix - get_block.ref_block_prefix .. This is
    a 32 bit number identifier (identify the same block referenced in `ref_block_num`).
  
    @property {string} expiration - This is based on the head block time from the
    blockchain.  Be careful to suffix a Z if required (as with Firefox and JavaScript)
    to ensure this date string is interpreted as Zulu time.
  
    Example: `new Date(new Date(info.head_block_time + 'Z').getTime() + expireInSeconds * 1000).toISOString().split('.')[0]`
  */

  /**
    Consult the blockchain and gather information for use in a new signed transaction.
    For Transaction as Proof of Stake (TaPOS), 32 bits of a recent block Id is included.
    Because all transactions use TaPOS, this solves the nothing at stake attack.
  
    This is usually called for every transaction or maybe cached per block.  Although
    longer caching is possible, a longer cache time increases the risk of a
    transaction replay attack.
  
    @arg {number} expireInSeconds - How many seconds until expiration
    @arg {function(error, headers)} callback {@link headers}
    @see {headers}
    @example eos.createTransaction(60, (error, headers) => {})
  */
};function createTransaction(api) {
  var expireInSeconds = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 60;
  var callback = arguments[2];

  if (!callback) {
    throw new TypeError('callback parameter is required');
  }
  api.getInfo(checkError(callback, function (info) {
    var chainDate = new Date(info.head_block_time + 'Z');

    api.getBlock(info.last_irreversible_block_num, checkError(callback, function (block) {
      var expiration = new Date(chainDate.getTime() + expireInSeconds * 1000);

      var ref_block_num = info.last_irreversible_block_num & 0xFFFF;

      var headers = {
        expiration: expiration.toISOString().split('.')[0],
        ref_block_num: ref_block_num,
        ref_block_prefix: block.ref_block_prefix,
        max_net_usage_words: 0,
        max_cpu_usage_ms: 0,
        delay_sec: 0,
        context_free_actions: [],
        actions: [],
        signatures: [],
        transaction_extensions: []
      };
      callback(null, headers);
    }));
  }));
}

var checkError = function checkError(parentErr, parrentRes) {
  return function (error, result) {
    if (error) {
      parentErr(error);
    } else {
      parrentRes(result);
    }
  };
};