Improve Navigation script

- remove unused paramaters
- decrease complexity of updateNavigationControls

Resources/Public/JavaScript/PageView/Navigation.js

@@ -85,14 +85,15 @@ class dlfNavigation {
  this.docController.changePage(pageNo);
  });
 
- this.docController.eventTarget.addEventListener('tx-dlf-stateChanged', this.onStateChanged.bind(this));
+ this.docController.eventTarget.addEventListener('tx-dlf-stateChanged', () => {
+ this.onStateChanged();
+ });
  }
 
  /**
  * @private
- * @param {dlf.StateChangeEvent} e
  */
- onStateChanged(e) {
+ onStateChanged() {
  this.updateNavigationControls();
  }
 
@@ -111,27 +112,16 @@ class dlfNavigation {
  * Update DOM state of navigation buttons and dropdown. (For example,
  * enable/disable the buttons depending on current page.)
  *
- * @param {number} pageNo
  * @private
  */
  updateNavigationControls() {
  const currentPageNo = this.docController.currentPageNo;
 
- for (const [key, value] of Object.entries(this.navigationButtons)) {
+ for (const value of Object.values(this.navigationButtons)) {
  const btnPageNo = value.getPage(currentPageNo);
- const isBtnPageVisible = this.docController.getVisiblePages(btnPageNo).some(page => page.pageNo === currentPageNo);
- if (!isBtnPageVisible && 1 <= btnPageNo && btnPageNo <= this.docController.numPages) {
- value.button.classList.remove('disabled');
- } else {
- value.button.classList.add('disabled');
- }
- // TODO(client-side): Check if it needs to be done always or only for not disabled buttons
+ this.toggleButtonDisabled(value.button, btnPageNo);
  this.updateUrl(value.button, btnPageNo);
-
- const textTemplate = value.button.getAttribute('data-text');
- if (textTemplate) {
- value.button.textContent = textTemplate.replace(/PAGE_STEPS/, this.getLongStep());
- }
+ this.updateText(value.button);
  }
 
  if (this.pageSelect instanceof HTMLSelectElement) {
@@ -140,11 +130,44 @@ class dlfNavigation {
  }
 
  /**
- * Update URLs of navigation buttons.
+ * Enable/disable the button depending on current page.
+ *
+ * @param {button} Element
+ * @param {pageNo}
+ *
+ * @private
+ */
+ toggleButtonDisabled(button, pageNo) {
+ const isBtnPageVisible = this.docController.getVisiblePages(pageNo).some(page => page.pageNo === this.docController.currentPageNo);
+ if (!isBtnPageVisible && 1 <= pageNo && pageNo <= this.docController.numPages) {
+ button.classList.remove('disabled');
+ } else {
+ button.classList.add('disabled');
+ }
+ }
+
+ /**
+ * Update URLs of navigation button.
+ * 
+ * @param {button} Element
+ *
+ * @private
+ */
+ updateUrl(button, pageNo) {
+ button.setAttribute('href', this.docController.makePageUrl(pageNo));
+ }
+
+ /**
+ * Update text of navigation button.
+ * 
+ * @param {button} Element
  *
  * @private
  */
- updateUrl(button, page) {
- button.setAttribute('href', this.docController.makePageUrl(page));
+ updateText(button) {
+ const textTemplate = button.getAttribute('data-text');
+ if (textTemplate) {
+ button.textContent = textTemplate.replace(/PAGE_STEPS/, this.getLongStep());
+ }
  }
 }