Add package.json support #74

README.md

@@ -34,7 +34,8 @@ Browserslist will use browsers criteria from:
 1. First argument.
 2. `BROWSERSLIST` environment variable.
 3. `browserslist` config file in current or parent directories.
-4. If the above methods did not produce a valid result, Browserslist will use defaults:
+4. `browserslist` key in `package.json` file in current or parent directories.
+5. If the above methods did not produce a valid result, Browserslist will use defaults:
    `> 1%, last 2 versions, Firefox ESR`.
 
 Multiple criteria are combined as a boolean `OR`. A browser version must match

index.js

@@ -239,12 +239,33 @@ browserslist.readConfig = function (from) {
     if ( typeof from === 'undefined' ) from = '.';
 
     var dirs = path.resolve(from).split(path.sep);
-    var config;
+    var config, configPath, pkg, pkgConfig, pkgPath;
     while ( dirs.length ) {
-        config = dirs.concat(['browserslist']).join(path.sep);
+        configPath = dirs.concat(['browserslist']).join(path.sep);
+        pkgPath = dirs.concat(['package.json']).join(path.sep);
 
-        if ( fs.existsSync(config) && fs.statSync(config).isFile() ) {
-            return browserslist.parseConfig( fs.readFileSync(config) );
+        if ( fs.existsSync(configPath) && fs.statSync(configPath).isFile() ) {
+            config = fs.readFileSync(configPath);
+        }
+
+        if ( fs.existsSync(pkgPath) && fs.statSync(pkgPath).isFile() ) {
+            try {
+                pkg = JSON.parse( fs.readFileSync(pkgPath) );
+                pkgConfig = pkg.browserslist;
+            } catch (e) {
+                console.warn('Could not parse ' + pkgPath);
+                console.warn(e.trace);
+            }
+        }
+
+        if (config && pkgConfig) {
+            throw new Error(dirs.join(path.sep) +
+            ' contains both browserslist and package.json' +
+            ' with browserslist key, this is potentially dangerous.');
+        } else if (config) {
+            return browserslist.parseConfig( config );
+        } else if (pkgConfig) {
+            return pkgConfig;
         }
 
         dirs.pop();

test/config.test.js

@@ -3,6 +3,8 @@ var browserslist = require('../');
 var path = require('path');
 
 var css = path.join(__dirname, 'fixtures', 'dir', 'test.css');
+var withBoth = path.join(__dirname, 'fixtures', 'withBoth', 'test.css');
+var withPackage = path.join(__dirname, 'fixtures', 'withPackage', 'test.css');
 
 it('parses queries', () => {
     expect(browserslist.parseConfig('ie 10\n> 1%')).toEqual(['ie 10', '> 1%']);
@@ -25,3 +27,11 @@ it('returns false on no config', () => {
 it('reads config', () => {
     expect(browserslist.readConfig(css)).toEqual(['ie 11', 'ie 10']);
 });
+
+it('reads config from package.json', () => {
+    expect(browserslist.readConfig(withPackage)).toEqual(['ie 9', 'ie 10']);
+});
+
+it('reads from dir wich contains both browserslist and package.json', () => {
+    expect(() => browserslist.readConfig(withBoth)).toThrow();
+});

test/fixtures/withBoth/browserslist

@@ -0,0 +1,3 @@
+# File for test
+ie 11
+ie 10

test/fixtures/withBoth/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "browserslist-example",
+  "browserslist": ["ie 9", "ie 10"]
+}

test/fixtures/withPackage/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "browserslist-example",
+  "browserslist": ["ie 9", "ie 10"]
+}