adding subscriptions

packages/web3-core-subscriptions/src/subscription.js

@@ -27,11 +27,15 @@ var errors = require('web3-core-helpers').errors;
 var EventEmitter = require('eventemitter3');
 var formatters = require('web3-core-helpers').formatters;
 
+function identity(value) {
+ return value;
+}
+
 function Subscription(options) {
  EventEmitter.call(this);
 
  this.id = null;
- this.callback = _.identity;
+ this.callback = identity;
  this.arguments = null;
  this.lastBlock = null; // "from" block tracker for backfilling events on reconnection
 
@@ -56,7 +60,7 @@ Subscription.prototype.constructor = Subscription;
  */
 
 Subscription.prototype._extractCallback = function (args) {
- if (_.isFunction(args[args.length - 1])) {
+ if (typeof args[args.length - 1] === 'function') {
  return args.pop(); // modify the args array!
  }
 };
@@ -136,7 +140,7 @@ Subscription.prototype._formatOutput = function (result) {
  */
 Subscription.prototype._toPayload = function (args) {
  var params = [];
- this.callback = this._extractCallback(args) || _.identity;
+ this.callback = this._extractCallback(args) || identity;
 
  if (!this.subscriptionMethod) {
  this.subscriptionMethod = args.shift();
@@ -226,7 +230,7 @@ Subscription.prototype.subscribe = function() {
 
  // Re-subscription only: continue fetching from the last block we received.
  // a dropped connection may have resulted in gaps in the logs...
- if (this.lastBlock && _.isObject(this.options.params)){
+ if (this.lastBlock && typeof this.options.params === 'object' && !!null ){
  payload.params[1] = this.options.params;
  payload.params[1].fromBlock = formatters.inputBlockNumberFormatter(this.lastBlock + 1);
  }
@@ -240,7 +244,7 @@ Subscription.prototype.subscribe = function() {
  this.options.params = payload.params[1];
 
  // get past logs, if fromBlock is available
- if(payload.params[0] === 'logs' && _.isObject(payload.params[1]) && payload.params[1].hasOwnProperty('fromBlock') && isFinite(payload.params[1].fromBlock)) {
+ if(payload.params[0] === 'logs' && typeof payload.params[1] === 'object' && !!payload.params[1] && payload.params[1].hasOwnProperty('fromBlock') && isFinite(payload.params[1].fromBlock)) {
  // send the subscription request
 
  // copy the params to avoid race-condition with deletion below this block
@@ -283,17 +287,17 @@ Subscription.prototype.subscribe = function() {
  // call callback on notifications
  _this.options.requestManager.addSubscription(_this, function(error, result) {
  if (!error) {
- if (!_.isArray(result)) {
+ if (!Array.isArray(result)) {
  result = [result];
  }
 
  result.forEach(function(resultItem) {
  var output = _this._formatOutput(resultItem);
 
  // Track current block (for gaps introduced by dropped connections)
- _this.lastBlock = _.isObject(output) ? output.blockNumber : null;
+ _this.lastBlock = typeof output === 'object' ? output.blockNumber : null;
 
- if (_.isFunction(_this.options.subscription.subscriptionHandler)) {
+ if (typeof _this.options.subscription.subscriptionHandler === 'function' ) {
  return _this.options.subscription.subscriptionHandler.call(_this, output);
  } else {
  _this.emit('data', output);