Arpith Siromoney 💬

Everybody stand back, I know Regular Expressions!

##(Spoiler alert: I don’t)

A few days ago, I talked about adding a full screen text input to my app, to make the experience of writing notes a little more pleasant. Today I’m adding a word count to my app, based on this answer on Stack Overflow:

var s = 'your long string with many words. and then a few word-with hy-phens. ';

// ["your", "long", "string", "with", "many", "words.", "and", "then", "a", "few", "word-with", "hy-phens.", ""]

var wordCount = s.split(/\s+/).filter(w => (!!w)).length;

// 12, since the "" at the end of the array has been filtered out

We’re using the regular expression to split the string, and filtering out empty “words”. Adding this code to the React Native component is straightforward — in our page’s constructor, we’ll add the following:

this.updateKeyboardSpace = (frames) => {
  var change;
  if (frames.endCoordinates) change = frames.endCoordinates.height;
  else change = frames.end.height;
  this.setState({height: this.state.height — change, isKeyboardUp: true});
};
this.resetKeyboardSpace = () => this.setState({height: this.state.fullHeight, isKeyboardUp: false});
this.updateWordCount = (text) => this.setState({wordCount: text.split(/\s+/).filter(w => !!w).length});

Our render function now looks like:

render() {
  if (this.state.isKeyboardUp) var title = <text></text>;
  else var title = <text style="{styles.title}">{this.state.wordCount} words</text>;
      
  return (
    <view style="{styles.page}" onlayout="{(ev)"> {
      // 80 is for the navbar on top
      var fullHeight = ev.nativeEvent.layout.height — 80;
      this.setState({height: fullHeight, fullHeight: fullHeight});
    }}>
        
      <navbar leftbutton="{this.cancelButton}" title="{title}" rightbutton="{this.postButton}/"><scrollview keyboarddismissmode="interactive"><textinput multiline="{true}" onchangetext="{(text)"> {
            this.state.post.data = text;
            this.updateWordCount(text);
          }}
          defaultValue={this.state.post.data}
          autoFocus={true}
          style={[styles.input, {height:this.state.height}]}
        />
      </textinput></scrollview></navbar></view>
  );
}

There are two things to look at here: (a) we only display the word count when the keyboard is down, and (b) we update the word count when the TextInput’s text changes. This fixes #43.