The drop-down list references database data JS to write randomly generated QR code

What should you do when you need a QR code with the content you want to represent or the web page you want to enter?

Today, let's look at the generation of a random QR Code:

Tools used:

Microsoft Visual Studio 2010

SQL Server Management Studio

First, we have to introduce two libraries:

<script type="text/javascript" src="http://static.runoob.com/assets/jquery/2.0.3/jquery.min.js"></script>
    <script type="text/javascript" src="http://static.runoob.com/assets/qrcode/qrcode.min.js"></script>

Then we have to introduce a control:

<asp:DropDownList ID="DropDownList2" runat="server" Height="16px" Width="322px" 
                            AutoPostBack="True"   onchange="makeCode()" >
                        </asp:DropDownList>

This control is a drop-down list control onchange="makeCode()" the method is to call the following JS method

Next is the JS method of generating QR code

<script type="text/javascript">
    var qrcode = new QRCode(document.getElementById("qrcode"), {
        width: 100,
        height: 100
    });

    function makeCode() {
            var elText = document.getElementById("DropDownList2");
            if (!elText.value) {
                elText.focus();
                return;
            }
            qrcode.makeCode(elText.value);
        
    }

    makeCode();

    $("#text").
	on("blur", function () {
	    makeCode();
	}).
	on("keydown", function (e) {
	    if (e.keyCode == 13) {
	        makeCode();
	    }
	});
</script>

The DropDownList2 in the database calls the data in the database, and the incoming data is DropDownList2.SelectedValue

If you don't understand the drop-down method, you can use the input box method directly.

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="ko" lang="ko">
<head>
<title>Javascript QR code generator: QRCode</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no" />
<script type="text/javascript" src="http://static.runoob.com/assets/jquery/2.0.3/jquery.min.js"></script>
<script type="text/javascript" src="http://static.runoob.com/assets/qrcode/qrcode.min.js"></script>
</head>
<body>
<input id="text" type="text" value="http://www.runoob.com" style="width:80%" /><br />
<div id="qrcode" style="width:100px; height:100px; margin-top:15px;"></div>

<script type="text/javascript">
var qrcode = new QRCode(document.getElementById("qrcode"), {
	width : 100,
	height : 100
});

function makeCode () {		
	var elText = document.getElementById("text");
	
	if (!elText.value) {
		alert("Input a text");
		elText.focus();
		return;
	}
	
	qrcode.makeCode(elText.value);
}

makeCode();

$("#text").
	on("blur", function () {
		makeCode();
	}).
	on("keydown", function (e) {
		if (e.keyCode == 13) {
			makeCode();
		}
	});
</script>
</body>
</html>

It is also necessary to introduce two libraries: jquery.min.js and qrcode.min.js

Keywords: QRCode Javascript JQuery Database

Added by webrajesh on Fri, 03 Jan 2020 04:06:08 +0200

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The drop-down list references database data JS to write randomly generated QR code

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