I am using a javascript library to implement a QR reader so when I get the code I store it in a variable that I send to a textbox, what I need to know is how to send it to a procedure to insert the data every time it changes textbox content without using buttons.

Here is the code:

<asp:TextBox ID="txt_Person_Nm" runat="server" CssClass="form-control" ReadOnly="true" ToolTip="Person ID"></asp:TextBox>
<asp:HiddenField ID="HiddenField1" runat="server"/>

And the function: 

        <div class="col-md-6">
	    <div class="form-group row">
		<video id="preview" class="col-lg-12"></video>
		<script type="text/javascript">
			let scanner = new Instascan.Scanner({ video: document.getElementById('preview') });
			scanner.addListener('scan', function (contenido) {
				var test = contenido.toString();
				document.getElementById('<%= HiddenField1.ClientID %>').value = test;
				$("#<%= txt_Person_Nm.ClientID %>").val($('#<%= HiddenField1.ClientID %>').val());
			});
			Instascan.Camera.getCameras().then(function (cameras) {
				if (cameras.length > 0) {
					scanner.start(cameras[0]);
				} else {
					console.error('There is no camara');
				}
			}).catch(function (e) {
				console.error(e);
			});
		</script>
	    </div>
        </div>