From c15c1fa2ecb35a7a4aa434b991bc905f765a1734 Mon Sep 17 00:00:00 2001
From: Ivan Bunin <chernobelenkiy@gmail.com>
Date: Thu, 24 Jan 2019 15:18:52 +0300
Subject: [PATCH 1/2] add replace flag

---
 index.js                    | 20 +++++++++++++++++---
 spec/px-to-viewport.spec.js | 19 +++++++++++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/index.js b/index.js
index 7bcc46a..d2bb878 100755
--- a/index.js
+++ b/index.js
@@ -12,7 +12,8 @@ var defaults = {
   fontViewportUnit: 'vw',  // vmin is more suitable.
   selectorBlackList: [],
   minPixelValue: 1,
-  mediaQuery: false
+  mediaQuery: false,
+  replace: true
 };
 
 module.exports = postcss.plugin('postcss-px-to-viewport', function (options) {
@@ -36,9 +37,16 @@ module.exports = postcss.plugin('postcss-px-to-viewport', function (options) {
 
       if (blacklistedSelector(opts.selectorBlackList, decl.parent.selector)) return;
 
-      var unit = getUnit(decl.prop, opts)
+      var unit = getUnit(decl.prop, opts);
+      var value = decl.value.replace(pxRegex, createPxReplace(opts.viewportWidth, opts.minPixelValue, opts.unitPrecision, unit));
 
-      decl.value = decl.value.replace(pxRegex, createPxReplace(opts.viewportWidth, opts.minPixelValue, opts.unitPrecision, unit));
+      if (declarationExists(decl.parent, decl.prop, value)) return;
+
+      if (opts.replace) {
+        decl.value = value;
+      } else {
+        decl.parent.insertAfter(i, decl.clone({ value: value }));
+      }
     });
 
     if (opts.mediaQuery) {
@@ -77,3 +85,9 @@ function blacklistedSelector(blacklist, selector) {
     return selector.match(regex);
   });
 }
+
+function declarationExists(decls, prop, value) {
+    return decls.some(function (decl) {
+        return (decl.prop === prop && decl.value === value);
+    });
+}
\ No newline at end of file
diff --git a/spec/px-to-viewport.spec.js b/spec/px-to-viewport.spec.js
index 23632e2..f530ac5 100644
--- a/spec/px-to-viewport.spec.js
+++ b/spec/px-to-viewport.spec.js
@@ -36,6 +36,13 @@ describe('px-to-viewport', function() {
 
     expect(processed).toBe(expected);
   });
+
+  it('should not add properties that already exist', function () {
+      var expected = '.rule { font-size: 16px; font-size: 5vw; }';
+      var processed = postcss(pxToViewport()).process(expected).css;
+
+      expect(processed).toBe(expected);
+  });
 });
 
 describe('value parsing', function() {
@@ -196,3 +203,15 @@ describe('minPixelValue', function () {
       expect(processed).toBe(expected);
   });
 });
+
+describe('replace', function () {
+  it('should leave fallback pixel unit with root em value', function () {
+      var options = {
+          replace: false
+      };
+      var processed = postcss(pxToViewport(options)).process(basicCSS).css;
+      var expected = '.rule { font-size: 15px; font-size: 4.6875vw }';
+
+      expect(processed).toBe(expected);
+  });
+});
\ No newline at end of file

From 4dd92416539920c150cf53d2d66f3dcbd590ca7b Mon Sep 17 00:00:00 2001
From: Ivan Bunin <chernobelenkiy@gmail.com>
Date: Fri, 25 Jan 2019 14:41:20 +0300
Subject: [PATCH 2/2] update readme

---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index 21a16c5..ba118f4 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,7 @@ Default:
   fontViewportUnit: 'vw',  // vmin is more suitable.
   selectorBlackList: [],
   minPixelValue: 1,
+  replace: true,
   mediaQuery: false
 }
 ```
@@ -111,6 +112,7 @@ Default:
         - `[/^body$/]` will match `body` but not `.body`
 - `minPixelValue` (Number) Set the minimum pixel value to replace.
 - `mediaQuery` (Boolean) Allow px to be converted in media queries.
+- `replace` (Boolean) replaces rules containing rems instead of adding fallbacks.
 
 ### Use with gulp-postcss