多图上传

.boxContent .float{

float:left;
width : 2rem;
height: 2rem;
overflow: hidden;
border: 1px solid #CCCCCC;
border-radius: 0.1rem;
padding: 0.05rem;
margin: 0.05rem;

}

.boxContent img{

position: relative;

}

.boxContent .result{

width: 2rem;
height:2rem;
text-align: center;
box-sizing: border-box;

}

.boxContent .delete{

width: 2rem;
height:2rem;
position: absolute;
text-align: center;
line-height: 2rem;
z-index: 10;
font-size: 0.3rem;
background-color: rgba(255,255,255,0.8);
color: #777;
opacity: 0;
transition-duration:0.7s;
-webkit-transition-duration: 0.7s;

}

.delete:hover{

cursor: pointer;
opacity: 1;

}

            <label class="icon">App截图</label>
            
            <input type="file" id="file_input" name="file"  multiple/>
            <!--用input标签并选择type=file，记得带上multiple，不然就只能单选图片了-->
        
        <div class="boxContent"></div>

var dataArr = []// 储存所选图片的结果(文件名和base64数据)

window.onload = function(){

var input = document.getElementById("file_input");
var result;
var fd;  //FormData方式发送请求
// var oAdd = document.getElementById("add");
// var oInput = document.getElementById("file_input");
if(typeof FileReader==='undefined'){
    alert("抱歉，你的浏览器不支持 FileReader");
    input.setAttribute('disabled','disabled');
}else{
    input.addEventListener('change',readFile,false);
}     //handler
function readFile(){
    fd = new FormData();
    var iLen = this.files.length;
    var index = 0;
    for(var i=0;i<iLen;i++){
        if (!input['value'].match(/.jpg|.gif|.png|.jpeg|.bmp/i)){&emsp;&emsp;//判断上传文件格式
            return alert("上传的图片格式不正确，请重新选择");
        }
        var reader = new FileReader();
        reader.index = i;
        fd.append(i,this.files[i]);
        reader.readAsDataURL(this.files[i]);  //转成base64
        reader.fileName = this.files[i].name;
        // dataArr+=this.files[i]
        dataArr.push(this.files[i]);

        reader.onload = function(e){
            result = '<div class="delete">delete</div><div class="result"><img src="'+this.result+'" alt=""/></div>';
            var div = document.createElement('div');
            div.innerHTML = result;
            div['className'] = 'float';
            div['index'] = index;
           $('.boxContent').append(div);  &emsp;&emsp;//插入dom树
            var img = div.getElementsByTagName('img')[0];
            img.onload = function(){
                var nowHeight = ReSizePic(this); //设置图片大小
                this.parentNode.style.display = 'block';
                var oParent = this.parentNode;
                if(nowHeight){
                    oParent.style.paddingTop = (oParent.offsetHeight - nowHeight)/2 + 'px';
                }
            }

            div.onclick = function(){
                this.remove();                  // 在页面中删除该图片元素
                delete dataArr[this.index];  // 删除dataArr对应的数据

            }
            index++;
        }
    }
}

}

/* 用ajax发送fd参数时要告诉jQuery不要去处理发送的数据， 不要去设置Content-Type请求头才可以发送成功，否则会报“Illegal invocation”的错误， 也就是非法调用，所以要加上“processData: false,contentType: false,”

• */

function ReSizePic(ThisPic) {

var RePicWidth = 200; //这里修改为您想显示的宽度值

var TrueWidth = ThisPic.width; //图片实际宽度
var TrueHeight = ThisPic.height; //图片实际高度

if(TrueWidth>TrueHeight){
    //宽大于高
    var reWidth = RePicWidth;
    ThisPic.width = reWidth;
    //垂直居中
    var nowHeight = TrueHeight * (reWidth/TrueWidth);
    return nowHeight;  //将图片修改后的高度返回，供垂直居中用
}else{
    //宽小于高
    var reHeight = RePicWidth;
    ThisPic.height = reHeight;
}

}