Rename private attribute _element to _el

Change-Id: I9c7a31bd6844636737ffa6456562b997f5e370a3
diff --git a/dev/js/src/menu/item.js b/dev/js/src/menu/item.js
index 7ce7455..e369918 100644
--- a/dev/js/src/menu/item.js
+++ b/dev/js/src/menu/item.js
@@ -105,8 +105,8 @@
    */
   element : function () {
     // already defined
-    if (this._element !== undefined)
-      return this._element;
+    if (this._el !== undefined)
+      return this._el;
     
     // Create list item
     const li = document.createElement("li");
@@ -119,7 +119,7 @@
     // Append template
     li.appendChild(this.content());
     
-    return this._element = li;
+    return this._el = li;
   },
 
   /**
diff --git a/dev/js/src/menu/lengthField.js b/dev/js/src/menu/lengthField.js
index 8a6641d..eed90b7 100644
--- a/dev/js/src/menu/lengthField.js
+++ b/dev/js/src/menu/lengthField.js
@@ -12,8 +12,8 @@
 
   // Initialize lengthField object
   _init : function () {
-    this._element = document.createElement('div');
-    this._element.classList.add('lengthField');
+    this._el = document.createElement('div');
+    this._el.classList.add('lengthField');
     return this;
   },
 
@@ -36,7 +36,7 @@
    * Get the associated dom element.
    */
   element : function () {
-    return this._element;
+    return this._el;
   },
 
 
@@ -44,7 +44,7 @@
    * Add string to lengthField.
    */
   add : function (param) {
-    this._element.appendChild(document.createElement('span'))
+    this._el.appendChild(document.createElement('span'))
       .appendChild(document.createTextNode(param[0] + '--'));
   },
 
@@ -53,8 +53,8 @@
    * Remove all initialized values
    */
   reset : function () {
-    while (this._element.firstChild) {
-      this._element.firstChild.remove();
+    while (this._el.firstChild) {
+      this._el.firstChild.remove();
     };
   }
 });
diff --git a/dev/js/src/menu/prefix.js b/dev/js/src/menu/prefix.js
index e513e85..3930e45 100644
--- a/dev/js/src/menu/prefix.js
+++ b/dev/js/src/menu/prefix.js
@@ -17,19 +17,19 @@
     t._string = '';
 
     // Add prefix span
-    t._element = document.createElement('span');
-    t._element.classList.add('pref');
+    t._el = document.createElement('span');
+    t._el.classList.add('pref');
     // Connect action
 
     if (t["onclick"] !== undefined)
-      t._element["onclick"] = t.onclick.bind(t);
+      t._el["onclick"] = t.onclick.bind(t);
     
     return t;
   },
 
 
   _update : function () {
-    return this._element.innerHTML
+    return this._el.innerHTML
       = this._string;
   },
 
@@ -132,7 +132,7 @@
    * Get the associated dom element.
    */
   element : function () {
-    return this._element;
+    return this._el;
   },
 
 
diff --git a/dev/js/src/menu/slider.js b/dev/js/src/menu/slider.js
index 5897da2..dcc6fc5 100644
--- a/dev/js/src/menu/slider.js
+++ b/dev/js/src/menu/slider.js
@@ -60,12 +60,12 @@
     if (arguments.length === 1) {
       if (bool) {
 	      if (!this._active) {
-	        this._element.classList.add('active');
+	        this._el.classList.add('active');
 	        this._active = true;
 	      };
       }
       else if (this._active) {
-	      this._element.classList.remove('active');
+	      this._el.classList.remove('active');
 	      this._active = false;
       }
     };
@@ -140,7 +140,7 @@
    * Get the associated dom element.
    */
   element : function () {
-    return this._element;
+    return this._el;
   },
 
 
@@ -151,7 +151,7 @@
   reInit : function () {
 
     const t = this;
-    const s = t._element.style;
+    const s = t._el.style;
 
     // Do not show the slider, in case there is nothing to scroll
     if (t._length <= t._limit) {
@@ -179,7 +179,7 @@
     t._event = {};
     t._active = false;
 
-    const el = t._element = document.createElement('div');
+    const el = t._el = document.createElement('div');
     el.setAttribute('class', 'ruler');
 
     t._slider = el.appendChild(
@@ -204,7 +204,7 @@
 
   // Reinit height based on dom position
   _initClientHeight : function () {
-    this._rulerHeight  = this._element.clientHeight;
+    this._rulerHeight  = this._el.clientHeight;
     this._sliderHeight = this._slider.clientHeight;
   },