使用ajax上传图片

<div class="cert_img">
      <label>
        <input type="file" name="" onchange="fileImg()" id="certFrom">
        <img src="./img/选择图片.png" alt="" id="certImg">
      </label>
    </div>

.cert_img{
        width: 80%;
        height: 170px;
        margin-left: 10px;
      }
      .cert_img input{
        display: none
      }

<script>
      function fileImg() {
        var formData = new FormData();
        formData.append("file", $("#certFrom")[0].files[0]);
        $.ajax({
          url: "接口地址",
          type: 'POST',
          data: formData,
          dataType: 'json',
          cache: false,
          processData: false,    //不要处理发送的数据
          contentType: false,    //不要添加请求头
          success: function(data) {
            console.log(data);
            $('#certImg').attr("src",`http://域名+{data.url}`)    //上传图片预览
          },
          error: function(data) {
            console.log(data);
          }
        });
      }
    </script>