ES6-ify and lint all JS files. (#79)

* Enforce LF

* ES6-ify and lint all JS files.

13 files changed, 165 insertions, 136 deletions

diff --git a/examples/less/gulp/gulpfile.js b/examples/less/gulp/gulpfile.js
index 37e7afc..51600f9 100644
--- a/examples/less/gulp/gulpfile.js
+++ b/examples/less/gulp/gulpfile.js
@@ -1,14 +1,14 @@
 'use strict';
 
-const gulp = require('gulp'),
-  less = require('gulp-less');
+const gulp = require('gulp');
+const less = require('gulp-less');
 
-gulp.task('build', function () {
+gulp.task('build', () => {
   return gulp.src('./src/**/*.less')
     .pipe(less())
     .pipe(gulp.dest('./dest'));
 });
 
-gulp.task('watch', function () {
+gulp.task('watch', () => {
   gulp.watch('./src/**/*.less', ['build']);
 });
diff --git a/examples/less/node/index.js b/examples/less/node/index.js
index c6269fc..b263c93 100644
--- a/examples/less/node/index.js
+++ b/examples/less/node/index.js
@@ -1,24 +1,27 @@
-const fs = require('fs'),
-  less = require('less'),
-  str = fs.readFileSync(__dirname + '/src/main.less', 'utf8');
+'use strict';
 
-less
-  .render(
-    str,
-    {paths: [__dirname + '/src']}
-  )
-  .then(
-    function (output) {
-      fs.writeFile(__dirname + '/dest/main.css', output.css, function (err) {
-        if (!err) {
-          console.log('Responsive font sizes generated.');
-        }
-        else {
-          throw err;
-        }
-      });
-    },
-    function (error) {
-      throw error;
-    }
-  );
+const fs = require('fs');
+const path = require('path');
+const less = require('less');
+
+const str = fs.readFileSync(path.join(__dirname, '/src/main.less'), 'utf8');
+
+less.render(
+  str,
+  {
+    paths: [path.join(__dirname, '/src')]
+  }
+).then(
+  output => {
+    fs.writeFile(path.join(__dirname, '/dest/main.css'), output.css, err => {
+      if (err) {
+        throw err;
+      } else {
+        console.log('Responsive font sizes generated.');
+      }
+    });
+  },
+  error => {
+    throw error;
+  }
+);
diff --git a/examples/postcss/gulp/gulpfile.js b/examples/postcss/gulp/gulpfile.js
index f4111d7..9c56767 100644
--- a/examples/postcss/gulp/gulpfile.js
+++ b/examples/postcss/gulp/gulpfile.js
@@ -1,6 +1,9 @@
+'use strict';
+
 const gulp = require('gulp');
 const postcss = require('gulp-postcss');
 const rfs = require('../../..');
+
 const options = {
   twoDimensional: false,
   baseFontSize: 20,
@@ -21,6 +24,6 @@ gulp.task('build', () => {
     .pipe(gulp.dest('./dest'));
 });
 
-gulp.task('watch', function () {
+gulp.task('watch', () => {
   gulp.watch('./src/**/*.css', ['build']);
 });
diff --git a/examples/postcss/node/index.js b/examples/postcss/node/index.js
index f63b047..8ab9a1e 100644
--- a/examples/postcss/node/index.js
+++ b/examples/postcss/node/index.js
@@ -1,7 +1,11 @@
+'use strict';
+
 const fs = require('fs');
+const path = require('path');
 const postcss = require('postcss');
 const rfs = require('../../..');
-const css = fs.readFileSync(__dirname + '/src/main.css', 'utf8');
+
+const css = fs.readFileSync(path.join(__dirname, '/src/main.css'), 'utf8');
 const options = {
   twoDimensional: false,
   baseFontSize: 20,
@@ -16,11 +20,10 @@ const options = {
 
 const processedCss = postcss(rfs(options)).process(css).css;
 
-fs.writeFile(__dirname + '/dest/main.css', processedCss, (err) => {
+fs.writeFile(path.join(__dirname, '/dest/main.css'), processedCss, err => {
   if (err) {
     throw err;
-  }
-  else {
+  } else {
     console.log('Responsive font sizes generated.');
   }
 });
diff --git a/examples/scss/gulp/gulpfile.js b/examples/scss/gulp/gulpfile.js
index 62782e9..f46a31d 100644
--- a/examples/scss/gulp/gulpfile.js
+++ b/examples/scss/gulp/gulpfile.js
@@ -1,14 +1,14 @@
 'use strict';
 
-const gulp = require('gulp'),
-  sass = require('gulp-sass');
+const gulp = require('gulp');
+const sass = require('gulp-sass');
 
-gulp.task('build', function () {
+gulp.task('build', () => {
   return gulp.src('./src/**/*.scss')
     .pipe(sass().on('error', sass.logError))
     .pipe(gulp.dest('./dest'));
 });
 
-gulp.task('watch', function () {
+gulp.task('watch', () => {
   gulp.watch('./src/**/*.scss', ['build']);
 });
diff --git a/examples/scss/node/index.js b/examples/scss/node/index.js
index dde62f0..77baa8e 100644
--- a/examples/scss/node/index.js
+++ b/examples/scss/node/index.js
@@ -1,22 +1,24 @@
+'use strict';
+
 const fs = require('fs');
+const path = require('path');
 const sass = require('node-sass');
 
 sass.render({
-    file: __dirname + '/src/main.scss', outFile: __dirname + '/dest/main.css',
-  }, function (error, result) { // node-style callback from v3.0.0 onwards
-    if (!error) {
-      // No errors during the compilation, write this result on the disk
-      fs.writeFile(__dirname + '/dest/main.css', result.css, function (err) {
-        if (!err) {
-          console.log('Responsive font sizes generated.');
-        }
-        else {
-          throw err;
-        }
-      });
-    }
-    else {
-      throw error;
-    }
+  file: path.join(__dirname, '/src/main.scss'),
+  outFile: path.join(__dirname, '/dest/main.css')
+}, (error, result) => { // Node-style callback from v3.0.0 onwards
+  if (error) {
+    throw error;
+  } else {
+    // No errors during the compilation, write this result on the disk
+    fs.writeFile(path.join(__dirname, '/dest/main.css'), result.css, err => {
+      if (err) {
+        throw err;
+      } else {
+        console.log('Responsive font sizes generated.');
+      }
+    });
   }
+}
 );
diff --git a/examples/stylus/gulp/gulpfile.js b/examples/stylus/gulp/gulpfile.js
index fb5d134..3ea42bd 100644
--- a/examples/stylus/gulp/gulpfile.js
+++ b/examples/stylus/gulp/gulpfile.js
@@ -1,14 +1,14 @@
 'use strict';
 
-const gulp = require('gulp'),
-  stylus = require('gulp-stylus');
+const gulp = require('gulp');
+const stylus = require('gulp-stylus');
 
-gulp.task('build', function () {
+gulp.task('build', () => {
   return gulp.src('./src/**/*.styl')
     .pipe(stylus())
     .pipe(gulp.dest('./dest'));
 });
 
-gulp.task('watch', function () {
+gulp.task('watch', () => {
   gulp.watch('./src/**/*.styl', ['build']);
 });
diff --git a/examples/stylus/node/index.js b/examples/stylus/node/index.js
index 427bb39..62ae685 100644
--- a/examples/stylus/node/index.js
+++ b/examples/stylus/node/index.js
@@ -1,18 +1,22 @@
-const fs = require('fs'),
-  stylus = require('stylus'),
-  str = fs.readFileSync(__dirname + '/src/main.styl', 'utf8');
+'use strict';
 
-stylus.render(str, {filename: __dirname + '/src/main.styl'}, function (err, css) {
+const fs = require('fs');
+const path = require('path');
+const stylus = require('stylus');
+
+const str = fs.readFileSync(path.join(__dirname, '/src/main.styl'), 'utf8');
+
+stylus.render(str, {
+  filename: path.join(__dirname, '/src/main.styl')
+}, (err, css) => {
   if (err) {
     throw err;
-  }
-  else {
-    fs.writeFile(__dirname + '/dest/main.css', css, function (err) {
-      if (!err) {
-        console.log('Responsive font sizes generated.');
-      }
-      else {
+  } else {
+    fs.writeFile(path.join(__dirname, '/dest/main.css'), css, err => {
+      if (err) {
         throw err;
+      } else {
+        console.log('Responsive font sizes generated.');
       }
     });
   }
diff --git a/postcss.js b/postcss.js
index 7263b93..e394a66 100644
--- a/postcss.js
+++ b/postcss.js
@@ -8,7 +8,7 @@
 
 const postcss = require('postcss');
 
-module.exports = postcss.plugin('postcss-rfs', function (opts) {
+module.exports = postcss.plugin('postcss-rfs', opts => {
   const BREAKPOINT_ERROR = 'breakpoint option is invalid, it must be set in `px`, `rem` or `em`.';
   const BREAKPOINT_UNIT_ERROR = 'breakpointUnit option is invalid, it must be `px`, `rem` or `em`.';
   const BASE_FONT_SIZE_ERROR = 'baseFontSize option is invalid, it must be set in `px` or `rem`.';
@@ -28,16 +28,15 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
     safariIframeResizeBugFix: false,
     enableResponsiveFontSizes: true
   };
+
   opts = Object.assign(defaultOptions, opts);
 
   if (typeof opts.baseFontSize !== 'number') {
     if (opts.baseFontSize.endsWith('px')) {
       opts.baseFontSize = parseFloat(opts.baseFontSize);
-    }
-    else if (opts.baseFontSize.endsWith('rem')) {
+    } else if (opts.baseFontSize.endsWith('rem')) {
       opts.baseFontSize = parseFloat(opts.baseFontSize) / opts.remValue;
-    }
-    else {
+    } else {
       console.error(BASE_FONT_SIZE_ERROR);
     }
   }
@@ -45,26 +44,22 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
   if (typeof opts.breakpoint !== 'number') {
     if (opts.breakpoint.endsWith('px')) {
       opts.breakpoint = parseFloat(opts.breakpoint);
-    }
-    else if (opts.breakpoint.endsWith('em')) {
+    } else if (opts.breakpoint.endsWith('em')) {
       opts.breakpoint = parseFloat(opts.breakpoint) * opts.remValue;
-    }
-    else {
+    } else {
       console.error(BREAKPOINT_ERROR);
     }
   }
 
-  return function (css) {
-
-    css.walkRules(function (rule) {
-
+  return css => {
+    css.walkRules(rule => {
       if (rule.selector.includes(DISABLE_RESPONSIVE_FONT_SIZE_SELECTOR)) {
         return;
       }
 
-      rule.walkDecls(function (decl) {
+      rule.walkDecls(decl => {
         // Skip if property is not in propList
-        if (opts.propList.indexOf(decl.prop) === -1) {
+        if (!opts.propList.includes(decl.prop)) {
           return;
         }
 
@@ -80,18 +75,16 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
         let value = parseFloat(decl.value);
 
         // Multiply by remValue if value is in rem
-        if (decl.value.indexOf('rem') > -1) {
+        if (decl.value.includes('rem')) {
           value *= opts.remValue;
         }
 
         // Render value in desired unit
         if (opts.fontSizeUnit === 'px') {
-          decl.value = toFixed(value, opts.unitPrecision) + 'px';
-        }
-        else if (opts.fontSizeUnit === 'rem') {
-          decl.value = toFixed(value / opts.remValue, opts.unitPrecision) + 'rem';
-        }
-        else {
+          decl.value = `${toFixed(value, opts.unitPrecision)}px`;
+        } else if (opts.fontSizeUnit === 'rem') {
+          decl.value = `${toFixed(value / opts.remValue, opts.unitPrecision)}rem`;
+        } else {
           console.error('fontSizeUnit option is not valid, it must be `px` or `rem`.');
         }
 
@@ -101,7 +94,7 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
         }
 
         // Calculate font-size and font-size difference
-        let baseFontSize = opts.baseFontSize + (value - opts.baseFontSize) / opts.factor;
+        let baseFontSize = opts.baseFontSize + ((value - opts.baseFontSize) / opts.factor);
         const fontSizeDiff = value - baseFontSize;
 
         // Divide by remValue if needed
@@ -111,7 +104,7 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
 
         const viewportUnit = opts.twoDimensional ? 'vmin' : 'vw';
 
-        value = 'calc(' + toFixed(baseFontSize, opts.unitPrecision) + opts.fontSizeUnit + ' + ' + toFixed((fontSizeDiff * 100 / opts.breakpoint), opts.unitPrecision) + viewportUnit + ')';
+        value = `calc(${toFixed(baseFontSize, opts.unitPrecision)}${opts.fontSizeUnit} + ${toFixed(fontSizeDiff * 100 / opts.breakpoint, opts.unitPrecision)}${viewportUnit})`;
 
         const mediaQuery = postcss.atRule(renderMediaQuery(opts));
         let rule_selector = rule.selector;
@@ -121,23 +114,27 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
           const selectors = rule.selector.split(',');
           let ruleSelector = '';
 
-          for (let selector of selectors) {
-            ruleSelector += ENABLE_RESPONSIVE_FONT_SIZE_SELECTOR + ' ' + selector + ',\n';
-            ruleSelector += selector + ENABLE_RESPONSIVE_FONT_SIZE_SELECTOR + ',\n';
+          for (const selector of selectors) {
+            ruleSelector += `${ENABLE_RESPONSIVE_FONT_SIZE_SELECTOR} ${selector},\n`;
+            ruleSelector += `${selector + ENABLE_RESPONSIVE_FONT_SIZE_SELECTOR},\n`;
           }
+
           rule_selector = ruleSelector.slice(0, -2);
         }
 
-
         const mediaQueryRule = postcss.rule({
           selector: rule_selector,
           source: rule.source
         });
-        mediaQueryRule.append(decl.clone({value: value}));
+
+        mediaQueryRule.append(decl.clone({value}));
 
         // Safari iframe resize bug: https://github.com/twbs/rfs/issues/14
         if (opts.safariIframeResizeBugFix) {
-          mediaQueryRule.append(postcss.decl({ prop: 'min-width', value: '0vw' }));
+          mediaQueryRule.append(postcss.decl({
+            prop: 'min-width',
+            value: '0vw'
+          }));
         }
 
         mediaQuery.append(mediaQueryRule);
@@ -148,52 +145,58 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
           const selectors = rule.selector.split(',');
           let ruleSelector = '';
 
-          for (let selector of selectors) {
-            ruleSelector += selector + ',\n';
-            ruleSelector += DISABLE_RESPONSIVE_FONT_SIZE_SELECTOR + ' ' + selector + ',\n';
-            ruleSelector += selector + DISABLE_RESPONSIVE_FONT_SIZE_SELECTOR + ',\n';
+          for (const selector of selectors) {
+            ruleSelector += `${selector},\n`;
+            ruleSelector += `${DISABLE_RESPONSIVE_FONT_SIZE_SELECTOR} ${selector},\n`;
+            ruleSelector += `${selector + DISABLE_RESPONSIVE_FONT_SIZE_SELECTOR},\n`;
           }
-          ruleSelector = ruleSelector.slice(0, - 2);
 
-          const dc_rule = postcss.rule({
+          ruleSelector = ruleSelector.slice(0, -2);
+
+          const dcRule = postcss.rule({
             selector: ruleSelector,
             source: rule.source
           });
 
-          dc_rule.append(decl.clone());
-          rule.parent.insertAfter(rule, dc_rule);
-          decl.prev() || decl.next() ? decl.remove() : decl.parent.remove();
+          dcRule.append(decl.clone());
+          rule.parent.insertAfter(rule, dcRule);
+
+          if (decl.prev() || decl.next()) {
+            decl.remove();
+          } else {
+            decl.parent.remove();
+          }
         }
       });
     });
-
   };
 
-  function renderMediaQuery (opts) {
+  function renderMediaQuery(opts) {
     const mediaQuery = {
       name: 'media'
     };
 
     switch (opts.breakpointUnit) {
       case 'em':
-      case 'rem':
+      case 'rem': {
         const breakpoint = opts.breakpoint / opts.remValue;
 
         if (opts.twoDimensional) {
-          mediaQuery.params = '(max-width: ' + breakpoint + opts.breakpointUnit + '), (max-height: ' + breakpoint + opts.breakpointUnit + ')';
-        }
-        else {
-          mediaQuery.params = '(max-width: ' + breakpoint + opts.breakpointUnit + ')';
+          mediaQuery.params = `(max-width: ${breakpoint}${opts.breakpointUnit}), (max-height: ${breakpoint}${opts.breakpointUnit})`;
+        } else {
+          mediaQuery.params = `(max-width: ${breakpoint}${opts.breakpointUnit})`;
         }
+
         break;
+      }
 
       case 'px':
         if (opts.twoDimensional) {
-          mediaQuery.params = '(max-width: ' + opts.breakpoint + 'px), (max-height: ' + opts.breakpoint + 'px)';
-        }
-        else {
-          mediaQuery.params = '(max-width: ' + opts.breakpoint + 'px)';
+          mediaQuery.params = `(max-width: ${opts.breakpoint}px), (max-height: ${opts.breakpoint}px)`;
+        } else {
+          mediaQuery.params = `(max-width: ${opts.breakpoint}px)`;
         }
+
         break;
 
       default:
@@ -204,9 +207,10 @@ module.exports = postcss.plugin('postcss-rfs', function (opts) {
     return mediaQuery;
   }
 
-  function toFixed (number, precision) {
-    const multiplier = Math.pow(10, precision + 1),
-      wholeNumber = Math.floor(number * multiplier);
+  function toFixed(number, precision) {
+    const multiplier = Math.pow(10, precision + 1);
+    const wholeNumber = Math.floor(number * multiplier);
+
     return Math.round(wholeNumber / 10) * 10 / multiplier;
   }
 });
diff --git a/test/lib/result.js b/test/lib/result.js
index 8f59a36..add6340 100644
--- a/test/lib/result.js
+++ b/test/lib/result.js
@@ -1,49 +1,53 @@
+'use strict';
+
 // Packages
-const prettier = require("prettier");
-const fs = require("fs");
+const fs = require('fs');
+const prettier = require('prettier');
 const sass = require('node-sass');
 const less = require('less');
 const stylus = require('stylus');
 
+// Postcss
+const postcss = require('postcss');
+const rfs = require('../..');
+const postcsstests = require('../postcss/tests.js');
+
 // Strings
 const encoding = 'utf8';
 const dir = `${__dirname}/../`;
 
 // Functions
-const format = css => prettier.format(css, {parser: "css"}).replace(/(\n)(\n)/g, '$1');
+const format = css => prettier.format(css, {parser: 'css'}).replace(/(\n)(\n)/g, '$1');
 const getFileContent = (folder, id, ext) => fs.readFileSync(`${dir}${folder}/${id}.${ext}`, {encoding});
 
-// Postcss
-const postcss = require('postcss');
-const rfs = require('../../');
-const postcsstests = require('../postcss/tests.js');
 const postcsscss = getFileContent('postcss', 'main', 'css');
 
 // Exports
 module.exports = {
   // Return formatted expected result
-  expected: (id) => format(getFileContent('result', id, 'css')),
+  expected: id => format(getFileContent('result', id, 'css')),
 
   // Return parsed css
-  sass: (id) => format(sass.renderSync({file: `${dir}sass/${id}.scss`}).css.toString(encoding)),
+  sass: id => format(sass.renderSync({file: `${dir}sass/${id}.scss`}).css.toString(encoding)),
 
   // Return parsed css
-  less: (id) => {
-    return less.render(getFileContent('less', id, 'less'), {paths: [dir + 'less'], syncImport: true}).then((result) => {
+  less: id => {
+    return less.render(getFileContent('less', id, 'less'), {paths: [dir + 'less'], syncImport: true}).then(result => {
       return format(result.css);
     });
   },
 
-  stylus: (id) => {
+  stylus: id => {
     let formattedCSS = '';
     stylus.render(getFileContent('stylus', id, 'styl'), {filename: `${dir}stylus/${id}.styl`}, (err, css) => {
       if (err) {
         throw err;
       }
+
       formattedCSS = format(css);
     });
     return formattedCSS;
   },
 
-  postcss: (id) => format(postcss(rfs(postcsstests[id])).process(postcsscss).css)
+  postcss: id => format(postcss(rfs(postcsstests[id])).process(postcsscss).css)
 };
diff --git a/test/lib/tests.js b/test/lib/tests.js
index 361b0bf..45dc97d 100644
--- a/test/lib/tests.js
+++ b/test/lib/tests.js
@@ -1,3 +1,5 @@
+'use strict';
+
 module.exports = [
   {
     id: 'test-1',
@@ -38,5 +40,5 @@ module.exports = [
   {
     id: 'test-10',
     name: 'Include mixins multiple times'
-  },
+  }
 ];
diff --git a/test/postcss/tests.js b/test/postcss/tests.js
index 37fb0dd..b5f03d6 100644
--- a/test/postcss/tests.js
+++ b/test/postcss/tests.js
@@ -1,3 +1,5 @@
+'use strict';
+
 module.exports = {
   'test-1': {},
   'test-2': {
@@ -29,7 +31,7 @@ module.exports = {
     twoDimensional: true,
     factor: 5,
     class: true,
-    safariIframeResizeBugFix: true,
+    safariIframeResizeBugFix: true
   },
   'test-10': { // Not testable
     baseFontSize: '12px',
@@ -39,6 +41,6 @@ module.exports = {
     twoDimensional: true,
     factor: 5,
     class: true,
-    safariIframeResizeBugFix: true,
+    safariIframeResizeBugFix: true
   }
 };
diff --git a/test/test.js b/test/test.js
index 8340e86..9296599 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1,3 +1,5 @@
+/* eslint-env mocha */
+
 'use strict';
 
 const assert = require('assert');