chore: fix eslint warning

Author: wonsikin

.eslintignore

@@ -4,3 +4,4 @@ Example/android/
 ios/
 Example/ios/
 screenShoots/
+Example

index.js

@@ -171,8 +171,8 @@ export default class Barcode extends PureComponent {
         <Surface height={this.props.height} width={this.state.barCodeWidth}>
           <Shape d={this.state.bars} fill={this.props.lineColor} />
         </Surface>
-        if (typeof(this.props.text) != "undefined") {
-          <Text style={{color: this.props.textColor, width: this.state.barCodeWidth, textAlign: "center"}} >{this.props.text}</Text>
+        if (typeof(this.props.text) != 'undefined') {
+          <Text style={{color: this.props.textColor, width: this.state.barCodeWidth, textAlign: 'center'}} >{this.props.text}</Text>
         }
       </View>
     );