From e7fcbe962be6115c98bb8b2d6fdd7fb8f388d6c4 Mon Sep 17 00:00:00 2001
From: Taco de Wolff <tacodewolff@gmail.com>
Date: Sat, 2 Apr 2022 14:48:10 -0300
Subject: [PATCH] JS: merge sequential var declarations into another
 declaration

---
 js/js_test.go | 4 ++++
 js/vars.go    | 8 +++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/js/js_test.go b/js/js_test.go
index 1331fb113b..745051f1f7 100644
--- a/js/js_test.go
+++ b/js/js_test.go
@@ -334,6 +334,10 @@ func TestJS(t *testing.T) {
 		{`var a,b=c;b=a`, `var a,b=c;b=a`},
 		{`var{a}=f;var b=c,d=e;`, `var{a}=f,b=c,d=e`},
 		{`var a,b;a=1,b=2,c=3`, `var a=1,b=2;c=3`},
+		{`var a=[];var b={};var c=d,e=f`, `var a=[],b={},c=d,e=f`},
+		{`var a=[];var b={};var c=d,e=f`, `var a=[],b={},c=d,e=f`},
+		{`var a=[];var b;var c,e=f`, `var a=[],b,c,e=f`},
+		{`var a=[];f();var b;f();var c;f();var e=f`, `var a=[],b,c,e;f(),f(),f(),e=f`},
 		// TODO: test for variables renaming (first rename, then merge vars)
 
 		// function and method declarations
diff --git a/js/vars.go b/js/vars.go
index fe7bd446c6..26c780548a 100644
--- a/js/vars.go
+++ b/js/vars.go
@@ -261,7 +261,13 @@ func mergeVarDeclExprStmt(decl *js.VarDecl, exprStmt *js.ExprStmt, forward bool)
 			if forward {
 				item = commaExpr.List[len(commaExpr.List)-i-1]
 			}
-			if binaryExpr, ok := item.(*js.BinaryExpr); ok && binaryExpr.Op == js.EqToken {
+			if src, ok := item.(*js.VarDecl); ok {
+				// this happens when a variable declarations is converted to an expression
+				if mergeVarDecls(decl, src, forward) {
+					n++
+					continue
+				}
+			} else if binaryExpr, ok := item.(*js.BinaryExpr); ok && binaryExpr.Op == js.EqToken {
 				if v, ok := binaryExpr.X.(*js.Var); ok && v.Decl == js.VariableDecl {
 					if addDefinition(decl, v, binaryExpr.Y, forward) {
 						n++