thenGet.js

const language = require('@google-cloud/language');

async function isPositive(text) {
    // If you want to know detail of LanguageServiceClient,
    // See also
    // https://cloud.google.com/natural-language/docs/basics#interpreting_sentiment_analysis_values
    const lsclient = new language.LanguageServiceClient();

    const document = {
      content: text,
      type: 'PLAIN_TEXT',
    };

    // The value returned by the then function can be received in a variable with await.
    let sentiment = await lsclient.analyzeSentiment({document})
      .then(([result]) => {
        const sentiment = result.documentSentiment;
        return sentiment;
      })
      .catch((err) => {
        throw err;
      });

    if (sentiment.score > 0.0) {
      return true;
    } else {
      return false;
    }
}

let positive = await isPositive('I love you');