Merge pull request #21 from evrone/add-replace-flag

add replace flag

README.md

@@ -101,6 +101,7 @@ Default:
   selectorBlackList: [],
   minPixelValue: 1,
   mediaQuery: false,
+  replace: true,
   exclude: [] // ignore some files
 }
 ```
@@ -117,6 +118,7 @@ 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.
 - `exclude` (Array or Regexp) Ignore some files like 'node_modules'
     - If value is regexp, will ignore the matches files.
     - If value is array, the elements of the array are regexp.

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) {
@@ -50,9 +51,16 @@ 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) {
@@ -100,3 +108,9 @@ 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);
+    });
+}

spec/px-to-viewport.spec.js

@@ -43,6 +43,13 @@ 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() {
@@ -259,3 +266,15 @@ describe('exclude', function () {
     expect(processed).toBe(covered);
   });
 });
+
+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);
+  });
+});