title: What is the use of the " i " here? I use mongoose and Nodejs
body: <p><strong>controller:</strong>
  I use mongoose  and Nodejs , I don't know what is the use of the I here</p>
  <pre><code>    router.get('/more',(req, res) =&gt; {
  let moreCourses =  Courses.find({isPublished:true})
          .or([
              {price:{$gte:15}},
          {name:/.*by.*/i} &lt;=======================HERE
          ])
          .select({name:1,author:1,price:1})
          .then((moreCourses) =&gt;{
              res.status(200).json(moreCourses)
          })
          .catch((err) =&gt;{
              console.log(err);
          })
      })
  </code></pre>