我正在尝试通过单击提交按钮来更改内容的语言，但不确定为什么err会说Cannot read property 'querySelector' of undefined而且include #{language[index]}似乎也不起作用。是因为我们不能在include之后使用javascript吗？

此外，我想知道是否可以使用document.querySelector(".content").innerHTML=language.pug

extends base
block head
    link(rel='stylesheet',href='/css/contact.css',type='text/css')
block content
    <section class="contact"> 
        include nav
        <div class="contact-left">
            <div class="left-content"></div>
        <div class="contact-right">
            <div class="container language">
                <button type="button" class="btn btn-language">CH</button>
            </div>
        -const language=[chinese,english,korean]
        -var index=0
        -document.querySelector(".btn-language").addEventListener("click",()=>{
            -index++
            -if(index===3){
                -index=0
            -}
        -})

        include `#{language[index]}`
        </div>
        <canvas class="canvas"><canvas>
        <canvas class="canvas-3d"></canvas>
    </section>