how to fire event on file select

I've a form as

<form  onSubmit="return disableForm(this);" action="upload.php" method="post" name="f" id="wizecho" enctype="multipart/form-data">
    <input type="file" name="file" />
    <button onClick="return disableForm(this),ajaxUpload(this.form,'wizecho_upload.php', '&lt;br&gt;Uploading image please wait.....&lt;br&gt;'); return false;">
    	Upload Image
    </button>
</form>

It is to upload an image.

Here I need to click on the button to upload the image and I've to use onClick event. I want to remove the upload button and as soon as the file is selected at the input, I want to fire the event. How do I do that??

Use the change event on the file input.

$("#file").change(function(){
         //submit the form here
 });

You could subscribe for the onchange event on the input field:

<input type="file" id="file" name="file" />

and then:

document.getElementById('file').onchange = function() {
    // fire the upload here
};

This is an older question that needs a newer answer that will address @Christopher Thomas's concern above in the accept answer's comments. If you don't navigate away from the page and then select the file a second time, you need to clear the value when you click or do a touchstart(for mobile). The below will work even when you navigate away from the page and uses jquery:

//the HTML
<input type="file" id="file" name="file" />



//the JavaScript

/*resets the value to address navigating away from the page 
and choosing to upload the same file */	

$('#file').on('click touchstart' , function(){
    $(this).val('');
});


//Trigger now when you have selected any file 
$("#file").change(function(e) {
    //do whatever you want here
});

Solution for vue users, solving problem when you upload same file multiple times and @change event is not triggering:

 <input
      ref="fileInput"
      type="file"
      @click="onClick"
    />
  methods: {
    onClick() {
       this.$refs.fileInput.value = ''
       // further logic for file...
    }
  }

vanilla js using es6

document.querySelector('input[name="file"]').addEventListener('change', (e) => {
 const file = e.target.files[0];
  // todo: use file pointer
});

Do whatever you want to do after the file loads successfully.just after the completion of your file processing set the value of file control to blank string.so the .change() will always be called even the file name changes or not. like for example you can do this thing and worked for me like charm

  $('#myFile').change(function () {
    LoadFile("myFile");//function to do processing of file.
    $('#myFile').val('');// set the value to empty of myfile control.
    });

<input type="file" @change="onFileChange" class="input upload-input" ref="inputFile"/>

onFileChange(e) {
    //upload file and then delete it from input 
    self.$refs.inputFile.value = ''
}

<input id="fusk" type="file" name="upload" style="display: none;"
    onChange=" document.getElementById('myForm').submit();"
>