javascript - react-native onChangeText this.value is undefined -

i adding simple masking text input, date in dob field looks dd/mm/yyyy.

i have function handle that:

dateformat(text) {   if (text.match(/^\d{2}$/) !== null) {     this.value = text + '/';   } else if (text.match(/^\d{2}\/\d{2}$/) !== null) {     this.value = text + '/';   }   this.setstate({birthdate: this.value}); } 

i call function with:

onchangetext={(text) => this.dateformat(text)} 

the text passed correctly. however, this.value undefined , setting whatever, makes no difference.

what doing wrong?

i don't think need reference this.value, declare var value = text:

  onchangetext(text){     if (text.match(/^\d{2}$/) !== null) {      var value = text + '/';      this.setstate({birthdate: value})     } else if (text.match(/^\d{2}\/\d{2}$/) !== null) {       var value = text + '/';       this.setstate({birthdate: value});     } else {this.setstate({birthdate:text})}   } 

i've set on rnplay here, , seems working fine:

https://rnplay.org/apps/o9a7xq

'use strict';  var react = require('react-native'); var {   appregistry,   stylesheet,   text,   view,   textinput } = react;  var sampleapp = react.createclass({    getinitialstate(){     return {      birthdate: ''      }   },    onchangetext(text){     if (text.match(/^\d{2}$/) !== null) {       var value = text + '/';       this.setstate({birthdate: value})     } else if (text.match(/^\d{2}\/\d{2}$/) !== null) {         var value = text + '/';         this.setstate({birthdate: value});     } else {this.setstate({birthdate:text})}   },    render: function() {     return (       <view style={styles.container}>                <textinput value={this.state.birthdate} onchangetext={ (text) => this.onchangetext(text) } style={styles.textinput} />         <text>{this.state.birthdate}</text>       </view>     );   } });  var styles = stylesheet.create({   container: {     flex: 1,     margintop:60   },   textinput: {     height:70,     backgroundcolor: '#ddd'   } });  appregistry.registercomponent('sampleapp', () => sampleapp);