Adding the ability to create stop_loss_limit order with trailing delta (a.k.a trailing stop loss)

examples/trailing-stop-loss.js

@@ -0,0 +1,12 @@
+const Binance = require('node-binance-api');
+const binance = new Binance().options('options.json');
+
+const quantity = 1;
+const price = 2000;
+const trailingDelta = 500;
+
+await binance.sell("ETHUSDT", quantity, price, { 
+    timeInForce: 'GTC', 
+    trailingDelta: trailingDelta, 
+    type: 'STOP_LOSS_LIMIT'
+})

node-binance-api.js

@@ -400,6 +400,7 @@ let api = function Binance( options = {} ) {
          * LIMIT_MAKER
          */
         if ( typeof flags.icebergQty !== 'undefined' ) opt.icebergQty = flags.icebergQty;
+        if ( typeof flags.trailingDelta !== 'undefined' ) opt.trailingDelta = flags.trailingDelta;
         if ( typeof flags.stopPrice !== 'undefined' ) {
             opt.stopPrice = flags.stopPrice;
             if ( opt.type === 'LIMIT' ) throw Error( 'stopPrice: Must set "type" to one of the following: STOP_LOSS, STOP_LOSS_LIMIT, TAKE_PROFIT, TAKE_PROFIT_LIMIT' );

test.js

@@ -297,7 +297,7 @@ describe('Buy order advanced', function () {
 });
 
 describe('Sell Stop loess', function () {
-  it('Attempt to create a stop loss order', function (done) {
+  it('Attempt to create a stop loss order with a trailing delta', function (done) {
     let type = 'STOP_LOSS';
     let quantity = 1;
     let price = 0.069;
@@ -307,6 +307,17 @@ describe('Sell Stop loess', function () {
   }).timeout(TIMEOUT);
 });
 
+describe('Sell with trailing Stop loss', function () {
+  it('Attempt to create a stop loss order', function (done) {
+    let type = 'STOP_LOSS_LIMIT';
+    let quantity = 1;
+    let price = 0.069;
+    let delta = 100;
+    assert(typeof (binance.sell('ETHBTC', quantity, price, { trailingDelta: delta, type: type })) === 'undefined', WARN_SHOULD_BE_UNDEFINED);
+    done();
+  }).timeout(TIMEOUT);
+});
+
 describe('Iceberg sell order', function () {
   it('Attempt to create a sell order', function (done) {
     let quantity = 1;