feat: add deprecation warning for size prop

README.md

@@ -50,7 +50,7 @@ The props available are (shown with default values):
 ```js
 {
     value: '', // The value to encode in the code
-    size: 256, // Size of the code in pixels
+    size: 256, // Size of the code in pixels. This is obsolete and will be removed in the next major version!
     level: 'L', // QR Error correction level
     bgColor: '#FFFFFF', // Color of the bright squares
     fgColor: '#000000', // Color of the dark squares

src/components/qr-svg.js

@@ -4,6 +4,8 @@ import PropTypes from 'prop-types';
 const QRCodeImpl = require('qr.js/lib/QRCode');
 const ErrorCorrectLevel = require('qr.js/lib/ErrorCorrectLevel');
 
+let warningFired = false;
+
 export function QRCode({
     value = '',
     size,
@@ -12,6 +14,12 @@ export function QRCode({
     fgColor = '#000000',
     ...otherProps
 } = {}) {
+    if (size && !warningFired) {
+        /* eslint-disable no-console */
+        console.warn('The \'size\' prop is deprecated and will be removed in the next major version. Please use the \'style\', \'className\' or \'width\' props to size the code.');
+        /* eslint-enable no-console */
+        warningFired = true;
+    }
     // adapted from https://github.com/zpao/qrcode.react/blob/master/src/index.js
     const qrcode = new QRCodeImpl(-1, ErrorCorrectLevel[level]);
     qrcode.addData(value);