Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/@testing-library/jest-dom/dist/to-have-display-value.js

@@ -0,0 +1,32 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.toHaveDisplayValue = toHaveDisplayValue;
+var _utils = require("./utils");
+function toHaveDisplayValue(htmlElement, expectedValue) {
+  (0, _utils.checkHtmlElement)(htmlElement, toHaveDisplayValue, this);
+  const tagName = htmlElement.tagName.toLowerCase();
+  if (!['select', 'input', 'textarea'].includes(tagName)) {
+    throw new Error('.toHaveDisplayValue() currently supports only input, textarea or select elements, try with another matcher instead.');
+  }
+  if (tagName === 'input' && ['radio', 'checkbox'].includes(htmlElement.type)) {
+    throw new Error(`.toHaveDisplayValue() currently does not support input[type="${htmlElement.type}"], try with another matcher instead.`);
+  }
+  const values = getValues(tagName, htmlElement);
+  const expectedValues = getExpectedValues(expectedValue);
+  const numberOfMatchesWithValues = expectedValues.filter(expected => values.some(value => expected instanceof RegExp ? expected.test(value) : this.equals(value, String(expected)))).length;
+  const matchedWithAllValues = numberOfMatchesWithValues === values.length;
+  const matchedWithAllExpectedValues = numberOfMatchesWithValues === expectedValues.length;
+  return {
+    pass: matchedWithAllValues && matchedWithAllExpectedValues,
+    message: () => (0, _utils.getMessage)(this, this.utils.matcherHint(`${this.isNot ? '.not' : ''}.toHaveDisplayValue`, 'element', ''), `Expected element ${this.isNot ? 'not ' : ''}to have display value`, expectedValue, 'Received', values)
+  };
+}
+function getValues(tagName, htmlElement) {
+  return tagName === 'select' ? Array.from(htmlElement).filter(option => option.selected).map(option => option.textContent) : [htmlElement.value];
+}
+function getExpectedValues(expectedValue) {
+  return expectedValue instanceof Array ? expectedValue : [expectedValue];
+}