怎么动态改变背景图的url

Question

具体实现：

    改变img-box中img的src打的同时能够立刻同步到bgimg，以背景图的形式展现，"background-image":"url($('.img-box img').attr('src').substring(0,20))"，这里的url要怎么写

    

<div class="bgimg">

</div>

<div class="img-box">

    <img src="img/2.jpg" alt="">

</div>

$(function(){

        let h = document.documentElement.clientHeight;

        $(".bgimg").height(h) + "px";

        $(".bgimg").css({"background-image":"url($('.img-box img').attr('src').substring(0,20))"});

        console.log($('.img-box img').attr('src').substring(0,20));

            

        })

Answer 1

$(".bgimg").css({'background-image':'url(' + $('.img-box img').attr('src').substring(0,20) + ')"'});