title: Random commas appear in array ReactJS
body: <p>I am trying to create this memory game in ReactJS and I have made an array in which I add 4 random numbers. Now everytime I press play game I need to fill the array with 4 random numbers 0 to 3 but I keep getting random commas that come out of nowhere in the array. I am quite new to React so any help is appreciated.</p>
  <p>I have tried different methods of filling up the array but the commas still appear. P.S: keepArray was initialized just before the for loop.</p>
  <pre><code>for (let i = 0; i &lt; 4; i++) {
        let rand = Math.floor(Math.random() * 4)
        keepArray = [...keepArray + rand]
        console.log(keepArray)
      }
  </code></pre>