Support falsy value from fn rule (#1164)

* support falsy value from fn rule

* changelog

Author: kof

changelog.md

@@ -9,6 +9,7 @@ Since you are interested in what happens next, in case, you work for a for-profi
 ### Bug fixes
 
 - [react-jss] Fix nested dynamic rule updating ([1144](https://github.com/cssinjs/jss/pull/1144))
+- [jss] Support falsy value from fn rule ([1164](https://github.com/cssinjs/jss/pull/1164))
 
 ---
 

packages/css-jss/.size-snapshot.json

@@ -1,13 +1,13 @@
 {
   "dist/css-jss.js": {
-    "bundled": 57471,
-    "minified": 20270,
-    "gzipped": 6819
+    "bundled": 57601,
+    "minified": 20274,
+    "gzipped": 6822
   },
   "dist/css-jss.min.js": {
-    "bundled": 56717,
-    "minified": 19812,
-    "gzipped": 6608
+    "bundled": 56847,
+    "minified": 19816,
+    "gzipped": 6610
   },
   "dist/css-jss.cjs.js": {
     "bundled": 2919,

packages/jss-plugin-rule-value-function/.size-snapshot.json

@@ -1,23 +1,23 @@
 {
   "dist/jss-plugin-rule-value-function.js": {
-    "bundled": 2210,
-    "minified": 747,
-    "gzipped": 438
+    "bundled": 2340,
+    "minified": 751,
+    "gzipped": 440
   },
   "dist/jss-plugin-rule-value-function.min.js": {
-    "bundled": 2210,
-    "minified": 747,
-    "gzipped": 438
+    "bundled": 2340,
+    "minified": 751,
+    "gzipped": 440
   },
   "dist/jss-plugin-rule-value-function.cjs.js": {
-    "bundled": 1802,
-    "minified": 646,
-    "gzipped": 371
+    "bundled": 1928,
+    "minified": 650,
+    "gzipped": 373
   },
   "dist/jss-plugin-rule-value-function.esm.js": {
-    "bundled": 1724,
-    "minified": 582,
-    "gzipped": 324,
+    "bundled": 1850,
+    "minified": 586,
+    "gzipped": 328,
     "treeshaked": {
       "rollup": {
         "code": 12,

packages/jss-plugin-rule-value-function/src/function-rules.test.js

@@ -52,6 +52,9 @@ describe('jss-plugin-rule-value-function: Function rules', () => {
         .createStyleSheet(
           {
             a: data => {
+              if (data.removeAll) {
+                return null
+              }
               if (data.noDisplay) {
                 return {color: data.color}
               }
@@ -89,6 +92,18 @@ describe('jss-plugin-rule-value-function: Function rules', () => {
         }
       `)
     })
+
+    it('should remove all props', () => {
+      sheet.update({color: 'red'})
+      expect(sheet.toString()).to.be(stripIndent`
+        .a-id {
+          color: red;
+          display: block;
+        }
+      `)
+      sheet.update({removeAll: true})
+      expect(sheet.toString()).to.be('.a-id {}')
+    })
   })
 
   describe('fallbacks inside', () => {

packages/jss-plugin-rule-value-function/src/index.js

@@ -52,7 +52,9 @@ export default function functionPlugin() {
       // If we have a style function, the entire rule is dynamic and style object
       // will be returned from that function.
       if (fnRule) {
-        styleRule.style = fnRule(data)
+        // Empty object will remove all currently defined props
+        // in case function rule returns a falsy value.
+        styleRule.style = fnRule(data) || {}
       }
 
       const fnValues = styleRule[fnValuesNs]

packages/jss-preset-default/.size-snapshot.json

@@ -1,13 +1,13 @@
 {
   "dist/jss-preset-default.js": {
-    "bundled": 54715,
-    "minified": 19504,
-    "gzipped": 6471
+    "bundled": 54845,
+    "minified": 19508,
+    "gzipped": 6474
   },
   "dist/jss-preset-default.min.js": {
-    "bundled": 53961,
-    "minified": 19046,
-    "gzipped": 6262
+    "bundled": 54091,
+    "minified": 19050,
+    "gzipped": 6264
   },
   "dist/jss-preset-default.cjs.js": {
     "bundled": 1329,

packages/jss-starter-kit/.size-snapshot.json

@@ -1,13 +1,13 @@
 {
   "dist/jss-starter-kit.js": {
-    "bundled": 70257,
-    "minified": 29544,
-    "gzipped": 9093
+    "bundled": 70387,
+    "minified": 29548,
+    "gzipped": 9100
   },
   "dist/jss-starter-kit.min.js": {
-    "bundled": 69503,
-    "minified": 29086,
-    "gzipped": 8883
+    "bundled": 69633,
+    "minified": 29090,
+    "gzipped": 8886
   },
   "dist/jss-starter-kit.cjs.js": {
     "bundled": 2592,

packages/react-jss/.size-snapshot.json

@@ -1,13 +1,13 @@
 {
   "dist/react-jss.js": {
-    "bundled": 168992,
-    "minified": 58283,
-    "gzipped": 19042
+    "bundled": 169122,
+    "minified": 58287,
+    "gzipped": 19043
   },
   "dist/react-jss.min.js": {
-    "bundled": 112324,
-    "minified": 41678,
-    "gzipped": 14127
+    "bundled": 112454,
+    "minified": 41682,
+    "gzipped": 14129
   },
   "dist/react-jss.cjs.js": {
     "bundled": 27019,