Two new media queries related rules

lib/metadata/policies.js

@@ -464,7 +464,7 @@ var policies = {
     "cssColors": {
         "tool": "phantomas",
         "label": "Colors count",
-        "message": "<p>This is the number of different colors defined in CSS.</p><p>Your CSS project will be easier to maintain if you keep a small color set.</p>",
+        "message": "<p>This is the number of different colors defined in CSS.</p><p>Your CSS will be easier to maintain if you keep a small color set.</p>",
         "isOkThreshold": 30,
         "isBadThreshold": 150,
         "isAbnormalThreshold": 400,
@@ -522,6 +522,43 @@ var policies = {
             };
         }
     },
+    "cssBreakpoints": {
+        "tool": "mediaQueriesChecker",
+        "label": "Breakpoints count",
+        "message": "<p>This is the number of different breakpoints found in the stylesheets' media queries.</p><p>Please note this rule is based on <i>min-width</i>, <i>max-width</i>, <i>min-device-width</i> and <i>max-device-width</i> media queries only.</p><p>Your CSS will be easier to maintain if you keep a reasonable number of breakpoints. Try to make a fluid design - using percents - to avoid the creation of numerous breakpoints.</p>",
+        "isOkThreshold": 6,
+        "isBadThreshold": 40,
+        "isAbnormalThreshold": 60,
+        "hasOffenders": true,
+        "offendersTransformFn": function(offenders) {
+            var offendersTable = [];
+
+            for (var offender in offenders) {
+                offendersTable.push({
+                    breakpoint: offender,
+                    count: offenders[offender].count,
+                    pixels: offenders[offender].pixels
+                });
+            }
+
+            return offendersTable;
+        }
+    },
+    "cssMobileFirst": {
+        "tool": "mediaQueriesChecker",
+        "label": "Not mobile-first media queries",
+        "message": "<p>This is the number of media queries that address small screens.</p><p>The common good practice, when creating a responsive website, is to write it \"mobile-first\". More explanation in <a href=\"http://www.sitepoint.com/introduction-mobile-first-media-queries\" target=\"_blank\">this great article</a>.</p>",
+        "isOkThreshold": 25,
+        "isBadThreshold": 200,
+        "isAbnormalThreshold": 600,
+        "hasOffenders": true,
+        "offendersTransformFn": function(offenders) {
+            return {
+                count: offenders.length,
+                list: offenders
+            };
+        }
+    },
     "cssImports": {
         "tool": "phantomas",
         "label": "Uses of @import",

lib/metadata/scoreProfileGeneric.json

@@ -71,7 +71,9 @@
                 "cssComplexSelectors": 2,
                 "cssComplexSelectorsByAttribute": 1.5,
                 "cssColors": 0.5,
-                "similarColors": 0.5
+                "similarColors": 0.5,
+                "cssBreakpoints": 1,
+                "cssMobileFirst": 1
             }
         },
         "badCSS": {

lib/runner.js

@@ -4,6 +4,7 @@ var debug                   = require('debug')('ylt:runner');
 var phantomasWrapper        = require('./tools/phantomas/phantomasWrapper');
 var jsExecutionTransformer  = require('./tools/jsExecutionTransformer');
 var colorDiff               = require('./tools/colorDiff');
+var mediaQueriesChecker     = require('./tools/mediaQueriesChecker');
 var weightChecker           = require('./tools/weightChecker/weightChecker');
 var rulesChecker            = require('./rulesChecker');
 var scoreCalculator         = require('./scoreCalculator');
@@ -32,6 +33,9 @@ var Runner = function(params) {
         // Compare colors
         data = colorDiff.compareAllColors(data);
 
+        // Check media queries
+        data = mediaQueriesChecker.analyzeMediaQueries(data);
+
         // Redownload every file
         return weightChecker.recheckAllFiles(data);
 

lib/tools/mediaQueriesChecker.js

@@ -0,0 +1,168 @@
+var debug   = require('debug')('ylt:mediaQueriesChecker');
+var parseMediaQuery = require('css-mq-parser');
+var offendersHelpers = require('../offendersHelpers');
+
+
+var mediaQueriesChecker = function() {
+    'use strict';
+
+    var MOBILE_MIN_BREAKPOINT = 200;
+    var MOBILE_MAX_BREAKPOINT = 300;
+
+    this.analyzeMediaQueries = function(data) {
+        debug('Starting to check all media queries...');
+
+        var offenders = data.toolsResults.phantomas.offenders.cssMediaQueries;
+        var mediaQueries = (offenders) ? this.parseAllMediaQueries(offenders) : [];
+        
+        var notMobileFirstCount = 0;
+        var notMobileFirstOffenders = [];
+
+        var breakpointsOffenders = {};
+
+        for (var i = 0; i < mediaQueries.length; i++) {
+            var item = mediaQueries[i];
+
+            if (!item) {
+                continue;
+            }
+
+            if (item.isForMobile) {
+                notMobileFirstCount += item.mediaQuery.rules;
+                notMobileFirstOffenders.push(item.mediaQuery);
+            }
+
+            for (var j = 0; j < item.breakpoints.length; j++) {
+                var breakpointString = item.breakpoints[j].string;
+                if (!breakpointsOffenders[breakpointString]) {
+                    breakpointsOffenders[breakpointString] = {
+                        count: 1,
+                        pixels: item.breakpoints[j].pixels
+                    };
+                } else {
+                    breakpointsOffenders[breakpointString].count += 1;
+                }
+            }
+        }
+
+        data.toolsResults.mediaQueriesChecker = {
+            metrics: {
+                cssMobileFirst: notMobileFirstCount,
+                cssBreakpoints: Object.keys(breakpointsOffenders).length
+            },
+            offenders: {
+                cssMobileFirst: notMobileFirstOffenders,
+                cssBreakpoints: breakpointsOffenders
+            }
+        };
+
+        debug('End of media queries check');
+
+        return data;
+    };
+
+    this.parseAllMediaQueries = function(offenders) {
+        return offenders.map(this.parseOneMediaQuery);
+    };
+
+    this.parseOneMediaQuery = function(offender) {
+        var splittedOffender = offendersHelpers.cssOffenderPattern(offender);
+        var parts = /^@media (.*) \((\d+ rules)\)$/.exec(splittedOffender.css);
+
+        if (!parts) {
+            debug('Failed to parse media query ' + offender);
+            return false;
+        }
+
+        var rulesCount = parseInt(parts[2], 10);
+        var query = parts[1];
+
+        var isForMobile = false;
+        var breakpoints = [];
+
+        try {
+
+            var ast = parseMediaQuery(query);
+
+            var min = 0;
+            var max = Infinity;
+            var pixels;
+
+            ast.forEach(function(astItem) {
+                astItem.expressions.forEach(function(expression) {
+                    if (expression.feature === 'width' || expression.feature === 'device-width') {
+                        if (astItem.inverse === false) {
+                            if (expression.modifier === 'max') {
+                                pixels = toPixels(expression.value);
+                                max = Math.min(max, pixels);
+                                breakpoints.push({
+                                    string: expression.value,
+                                    pixels: pixels
+                                });
+                            } else if (expression.modifier === 'min') {
+                                pixels = toPixels(expression.value);
+                                min = Math.max(min, pixels);
+                                breakpoints.push({
+                                    string: expression.value,
+                                    pixels: pixels
+                                });
+                            }
+                        } else if (astItem.inverse === true) {
+                            if (expression.modifier === 'max') {
+                                pixels = toPixels(expression.value);
+                                min = Math.max(min, pixels);
+                                breakpoints.push({
+                                    string: expression.value,
+                                    pixels: pixels
+                                });
+                            } else if (expression.modifier === 'min') {
+                                pixels = toPixels(expression.value);
+                                max = Math.min(max, pixels);
+                                breakpoints.push({
+                                    string: expression.value,
+                                    pixels: pixels
+                                });
+                            }
+                        }
+                    }
+                });
+            });
+
+            isForMobile = (min <= MOBILE_MIN_BREAKPOINT && max >= MOBILE_MAX_BREAKPOINT && max !== Infinity);
+
+        } catch(error) {
+            debug('Failed to parse media query ' + offender);
+        }
+
+        return {
+            mediaQuery: {
+                query: query,
+                rules: rulesCount,
+                file: splittedOffender.file,
+                line: splittedOffender.line,
+                column: splittedOffender.column
+            },
+            isForMobile: isForMobile,
+            breakpoints: breakpoints
+        };
+    };
+
+    // Parses a size in em, pt (or px) and returns it in px
+    function toPixels(size) {
+        var splittedSize = /^([\d\.]+)(.*)/.exec(size);
+        var value = parseFloat(splittedSize[1]);
+        var unit = splittedSize[2];
+
+        if (unit === 'em') {
+            return value * 16;
+        }
+
+        if (unit === 'pt') {
+            return value / 12 * 16;
+        }
+
+        return value;
+    }
+};
+
+module.exports = new mediaQueriesChecker();