Js determines the file type and controls the form submission sample code
- 2020-03-29 23:47:05
- OfStack
The following code implements the control form submission
function shangchuan(){
var filepath = document.getElementById("file").value;
alert(filepath);
if(filepath==""){
alert(" Please choose the file to upload! ");
document.getElementById("file").disabled=true;
}
var extname=filepath.substr(filepath.length-3, filepath.length);
alert("extname::"+extname);
//var extname = filepath.substring(filepath.lastIndexOf(".")+1,filepath.length);
// extname = extname.toLowerCase();// Case handled
if(extname!= "bmp" && extname!= "jpg" && extname!= "gif"){
alert(" Can only upload bmp,jpg,gif Format of the picture! ");
document.getElementById("file").disabled=true;
}
else{
document.getElementById("file").disabled=false;
}
}
<tr>
<td><input name="file12" style="width:200px; height: 100px;" type="file" id="file" ></td>
</tr>
<tr>
<td align="center"><button onclick="shangchuan()" > Click on the upload </button></td>
</tr>