Use Preact for settings and show validation

src/settings/components/index.jsx

@@ -1,5 +1,6 @@
 import './site.scss';
 import { h, Component } from 'preact';
+import Input from './ui/input';
 import * as settingActions from 'settings/actions/setting';
 import * as validator from 'shared/validators/setting';
 
@@ -10,6 +11,9 @@ class SettingsComponent extends Component {
     this.state = {
       settings: {
         json: '',
+      },
+      errors: {
+        json: '',
       }
     };
     this.context.store.subscribe(this.stateChanged.bind(this));
@@ -35,39 +39,47 @@ class SettingsComponent extends Component {
         <h1>Configure Vim-Vixen</h1>
         <form className='vimvixen-settings-form'>
 
-          <p>Load settings from:</p>
-          <input type='radio' id='setting-source-json'
+          <Input
+            type='radio'
             name='source'
-            value='json'
-            onChange={this.bindAndSave.bind(this)}
-            checked={this.state.settings.source === 'json'} />
-          <label htmlFor='settings-source-json'>JSON</label>
+            label='Use plain JSON'
+            checked={this.state.settings.source === 'json'}
+            value='json' />
 
-          <textarea name='json' spellCheck='false'
-            onInput={this.validate.bind(this)}
+          <Input
+            type='textarea'
+            name='json'
+            label='Plane JSON'
+            spellCheck='false'
+            error={this.state.errors.json}
             onChange={this.bindValue.bind(this)}
             onBlur={this.bindAndSave.bind(this)}
-            value={this.state.settings.json} />
+            value={this.state.settings.json}
+          />
         </form>
       </div>
     );
   }
 
-  validate(e) {
-    try {
-      let settings = JSON.parse(e.target.value);
+  validate(target) {
+    if (target.name === 'json') {
+      let settings = JSON.parse(target.value);
       validator.validate(settings);
-      e.target.setCustomValidity('');
-    } catch (err) {
-      e.target.setCustomValidity(err.message);
     }
   }
 
   bindValue(e) {
-    let nextSettings = Object.assign({}, this.state.settings);
-    nextSettings[e.target.name] = e.target.value;
+    let next = Object.assign({}, this.state);
 
-    this.setState({ settings: nextSettings });
+    next.errors.json = '';
+    try {
+      this.validate(e.target);
+    } catch (err) {
+      next.errors.json = err.message;
+    }
+    next.settings[e.target.name] = e.target.value;
+
+    this.setState(next);
   }
 
   bindAndSave(e) {

src/settings/components/site.scss

@@ -1,4 +1,6 @@
 .vimvixen-settings-form {
+  padding: 2px;
+
   textarea[name=json] {
     font-family: monospace;
     width: 100%;

src/settings/components/ui/input.jsx

@@ -0,0 +1,50 @@
+import { h, Component } from 'preact';
+import './input.scss';
+
+class Input extends Component {
+
+  renderRadio(props) {
+    let inputClasses = 'form-field-input';
+    if (props.error) {
+      inputClasses += ' input-error';
+    }
+    return <div>
+      <label>
+        <input className={ inputClasses } type='radio' {...props} />
+        { props.label }
+      </label>
+    </div>;
+  }
+
+  renderTextArea(props) {
+    let inputClasses = 'form-field-input';
+    if (props.error) {
+      inputClasses += ' input-error';
+    }
+    return <div>
+      <label
+        className='form-field-label'
+        htmlFor={props.id}
+      >{ props.label }</label>
+      <textarea className={inputClasses} {...props} />
+
+      <p className='form-field-error'>{ this.props.error }</p>
+    </div>;
+  }
+
+  render() {
+    let { type } = this.props;
+
+    switch (this.props.type) {
+    case 'radio':
+      return this.renderRadio(this.props);
+    case 'textarea':
+      return this.renderTextArea(this.props);
+    default:
+      console.warn(`Unsupported input type ${type}`);
+    }
+    return null;
+  }
+}
+
+export default Input;

src/settings/components/ui/input.scss

@@ -0,0 +1,17 @@
+.form-field-label {
+  font-weight: bold
+}
+
+.form-field-error {
+  font-weight: bold;
+  color: red;
+  min-height: 1.5em;
+}
+
+.form-field-input {
+  padding: 4px;
+}
+
+.form-field-input.input-error {
+  box-shadow: 0 0 2px red;
+}