[FEATURE] allow per transaction fees to be set

src/js/ripple/transaction.js

@@ -612,7 +612,7 @@ Transaction.prototype.lastLedger = function(sequence) {
 
 /**
  * Set max fee. Submission will abort if this is exceeded. Specified fee must
- * be >= 0
+ * be >= 0.
  *
  * @param {Number} fee The proposed fee
  */
@@ -625,6 +625,23 @@ Transaction.prototype.maxFee = function(fee) {
   return this;
 };
 
+/*
+ * Set the fee user will pay to the network for submitting this transaction. 
+ * Specified fee must be >= 0.
+ *
+ * @param {Number} fee The proposed fee
+ *
+ * @returns {Transaction} calling instance for chaining
+ */
+Transaction.prototype.setFixedFee = function(fee) {
+  if (typeof fee === 'number' && fee >= 0) {
+    this._setFixedFee = true;
+    this.tx_json.Fee = String(fee);
+  }
+
+  return this;
+};
+
 /**
  * Filter invalid properties from path objects in a path array
  *

src/js/ripple/transactionmanager.js

@@ -200,6 +200,10 @@ TransactionManager.prototype._adjustFees = function() {
   };
 
   this._pending.forEach(function(transaction) {
+    if (transaction._setFixedFee === true) {
+      return;
+    }
+    
     var oldFee = transaction.tx_json.Fee;
     var newFee = transaction._computeFee();
 
@@ -239,7 +243,7 @@ TransactionManager.prototype._updatePendingStatus = function(ledger) {
   assert.strictEqual(typeof ledger, 'object');
   assert.strictEqual(typeof ledger.ledger_index, 'number');
 
-  this._pending.forEach(function(transaction) {
+  this._pending.forEach(function(transaction) {    
     switch (ledger.ledger_index - transaction.submitIndex) {
       case 4:
         transaction.emit('missing', ledger);

test/transaction-test.js

@@ -828,6 +828,23 @@ describe('Transaction', function() {
     assert.strictEqual(transaction._setMaxFee, true);
   });
 
+  it('Set Fixed Fee', function() {
+    var transaction = new Transaction();
+
+    transaction.setFixedFee('a');
+    assert(!transaction._setFixedFee);
+
+    transaction.setFixedFee(-1000);
+    assert(!transaction._setFixedFee);
+
+    transaction.setFixedFee(NaN);
+    assert(!transaction._setFixedFee);
+
+    transaction.setFixedFee(1000);
+    assert.strictEqual(transaction._setFixedFee, true);
+    assert.strictEqual(transaction.tx_json.Fee, '1000');
+  });
+
   it('Rewrite transaction path', function() {
     var transaction = new Transaction();