### Initialize QRCode with Options

Source: https://davidshimjs.github.io/qrcodejs

Configure QR code appearance and error correction level during initialization.

```javascript
var qrcode = new QRCode("test", {
    text: "http://jindo.dev.naver.com/collie",
    width: 128,
    height: 128,
    colorDark : "#000000",
    colorLight : "#ffffff",
    correctLevel : QRCode.CorrectLevel.H
});
```

--------------------------------

### Initialize Basic QRCode

Source: https://davidshimjs.github.io/qrcodejs

Basic implementation using a DOM element ID to render a QR code.

```html
<div id="qrcode"></div>
<script type="text/javascript">
new QRCode(document.getElementById("qrcode"), "http://jindo.dev.naver.com/collie");
</script>
```

--------------------------------

### Sample CSS Styling

Source: https://davidshimjs.github.io/qrcodejs

Basic CSS to define the dimensions and layout of the QR code container.

```css
#qrcode {
  width:160px;
  height:160px;
  margin-top:15px;
}
```

--------------------------------

### Sample HTML Structure

Source: https://davidshimjs.github.io/qrcodejs

HTML markup for an input field and container for the QR code.

```html
<input id="text" type="text" value="https://hogangnono.com" style="width:80%" /><br />
<div id="qrcode"></div>
```

--------------------------------

### Manage QRCode Methods

Source: https://davidshimjs.github.io/qrcodejs

Clear existing QR codes or generate new ones dynamically.

```javascript
qrcode.clear(); // clear the code.
qrcode.makeCode("http://naver.com"); // make another code.
```

--------------------------------

### Sample Interactive Logic

Source: https://davidshimjs.github.io/qrcodejs

JavaScript logic to update the QR code based on user input from an HTML text field.

```javascript
var qrcode = new QRCode("qrcode");

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();
    }
  });
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.