Property 'files' does not exist on type 'HTMLElement' solution

When getting the file in input in the vue project, an error occurs:

input code:

<el-form-item label="图片：">
   <el-input v-model="form.file"  type="file" id="file"></el-input>
</el-form-item>

Get the selected file code snippet:

var a = document.getElementById("file").files[0];

The following errors occur, but do not affect the operation of the project:

 Solution:

var a = document.getElementById("file")["files"];
console.log(a[0])

In this way, the error is gone.