js部分：
var btn = document.getElementById('showMax');
var mtclose = document.getElementsByClassName('mtclose')[0];
var modalBox = document.getElementById('modalBox');
btn.addEventListener('click', function(){
modalBox.style.display = "block";
});
mtclose.addEventListener('click', function(){
modalBox.style.display = "none";
});css部分：
.btn{
width: 100px;
height: 35px;
border-radius: 5px;
font-size: 16px;
color: #F97B39;
position: absolute;
top: 130px;
left: 160px;
opacity: 0.2;
cursor: pointer; /*鼠标小手*/
}
.btn:hover, .btn:focus{ /*focus 取得焦点状态*/
background-color: #8AA7F9;
opacity: 0.5;
color: #FFFFFF;
}
.modalBox{
display: none;
width: 100%;
height: 100%;
position: fixed;
left: 0;
top: 0;
z-index: 1000;
background-color: rgba(0,0,0,0.5);
}
.modalBox-matter{
display: flex; /*/*弹性布局*/
flex-flow: column nowrap;
justify-content: space-between; /*两端对齐*/
width: 50%;
height: 80%;
margin: 30px auto 100px;
border-radius:10px;
-webkit-animation: zoom 0.6s;
animation: zoom 0.6s;
resize: both;
overflow: auto;
}
@keyframes zoom{
from {transform: scale(0)}
to {transform: scale(1)}
}
.modalBox-header{
margin-left: 617px;
}
.mtclose{
color: #602E2A;
font-size: 3em;
font-weight: bold;
transition: all 0.3s;
/*z-index: 1010; */
}
.mtclose:hover, .mtclose:focus{
color: #602E2A;
cursor: pointer;
}
.modalBox-body{
padding: 10px;
font-size: 16px;
}关于使用 JavaScript怎么在实现一个模态框就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
