I have a textarea that needs green color for the line that begins with double slash(//).

<textarea id="code-init" spellcheck="false"></textarea>

now I have used following code to attempt what I thought,

document.getElementById("code-init").onkeyup = e => {

if(e.key === '/') {
    console.log(e.key)
    document.getElementById("code-init").onkeyup = e =>{
        if(e.key === '/')
            e.target.style.color = "green"
        document.getElementById("code-init").onkeyup = e =>{
            if(e.key === "Enter")
                e.target.style.color = "white"
         }
     }
  }
}