Fixes bug that was causing prefix to be multiplied in Immediately-Invoked Function Expressions (IIFE) with multiple variable declarations

Author: joaosamouco

lib/esshorten.js

@@ -79,6 +79,9 @@
                 prefix = '';
             }
             do {
+                if (tip.indexOf(prefix) === 0) {
+                    tip = tip.substr(prefix.length);
+                }
                 tip = utility.generateNextName(tip);
             } while (!this.passAsUnique(prefix + tip));
             return prefix + tip;

test/mangle.coffee

@@ -186,9 +186,17 @@ describe 'mangle:', ->
             expect(result.body[0].expression.id.name).to.equal 'name'
 
     describe '`renamePrefix` option:', ->
-        program = esprima.parse '(function name() { var i = 42; });'
 
         it 'prefixes identifier with the given value', ->
+            program = esprima.parse '(function name() { var i = 42; });'
             result = esshorten.mangle program,
                 renamePrefix: 'foo_'
             expect(result.body[0].expression.id.name.indexOf('foo_')).to.equal 0
+
+        it 'prefixes identifier inside IIFE without multiplying prefixes', ->
+            program = esprima.parse '(function name() { var i = 42; var a = 5; })();'
+            result = esshorten.mangle program,
+                renamePrefix: 'foo_'
+
+            expect(result.body[0].expression.callee.body.body[1].declarations[0].id.name.indexOf('foo_')).to.equal 0
+            expect(result.body[0].expression.callee.body.body[1].declarations[0].id.name.indexOf('foo_foo_')).to.equal -1