input上传图片file

方法一：

<input type="file" name="id_bank" class="layui-input" accept="image/jpg,image/jpeg,image/gif,image/png"  onchange="imgChange(event,'id_bank')">
<img src="" alt="" id="id_bank">

function imgChange(e, imageid) {
   //console.info(e.target.files[0]);//图片文件
    //console.log(e.target.value);//这个也是文件的路径和上面的dom.value是一样的
    var reader = new FileReader();
    reader.onload = (function (file) {
        return function (e) {
            //console.info(this.result); //这个就是base64的数据了
            document.getElementById(imageid).src = this.result;
        };
    })(e.target.files[0]);
    reader.readAsDataURL(e.target.files[0]);
};

方法二：

<input type="file" name="id_bank" id="id_bank_file" class="layui-input" accept="image/jpg,image/jpeg,image/gif,image/png"  onchange="changeFileImg('id_bank_file','id_bank')">
<img src="" alt="" id="id_bank">

function changeFileImg(inputId,imgId){
        let file = document.getElementById(inputId).files[0];
        var img = document.getElementById(imgId)
        var fileVal = document.getElementById(inputId).value;
        var windowURL = window.URL || window.webkitURL;
        var dataURL = windowURL.createObjectURL(file);
        if(fileVal){
            img.src = dataURL
        }
    };