Increase the usage of compound assignment operators

[elfring]

:eyes: Some source code analysis tools can help to find opportunities for improving software components. :thought_balloon: I propose to increase the usage of compound operators accordingly.

diff --git a/src/usr/share/rpimonitor/web/addons/custom/custom.js b/src/usr/share/rpimonitor/web/addons/custom/custom.js
index 5b74d77..85f2080 100644
--- a/src/usr/share/rpimonitor/web/addons/custom/custom.js
+++ b/src/usr/share/rpimonitor/web/addons/custom/custom.js
@@ -64,7 +64,7 @@ $(window).resize(function() {
 
 window.onbeforeunload = function (e) {
   if ( !customwarning ) return;
-  e = e || window.event;
+  e ||= window.event;
   message="Closing or refreshing this page will also close your connection.";
   if (e) {
     e.returnValue = message;
diff --git a/src/usr/share/rpimonitor/web/js/bootstrap.js b/src/usr/share/rpimonitor/web/js/bootstrap.js
index 53da1c7..6813f47 100644
--- a/src/usr/share/rpimonitor/web/js/bootstrap.js
+++ b/src/usr/share/rpimonitor/web/js/bootstrap.js
@@ -94,7 +94,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
 
     if (!selector) {
       selector = $this.attr('href')
-      selector = selector && selector.replace(/.*(?=#[^\s]*$)/, '') // strip for ie7
+      selector &&= selector.replace(/.*(?=#[^\s]*$)/, '') // strip for ie7
     }
 
     var $parent = $(selector)
@@ -192,7 +192,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
     var val  = $el.is('input') ? 'val' : 'html'
     var data = $el.data()
 
-    state = state + 'Text'
+    state += 'Text'
 
     if (data.resetText == null) $el.data('resetText', $el[val]())
 
@@ -372,7 +372,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
 
   Carousel.prototype.slide = function (type, next) {
     var $active   = this.$element.find('.item.active')
-    var $next     = next || $active[type]()
+    var $next ||= $active[type]()
     var isCycling = this.interval
     var direction = type == 'next' ? 'left' : 'right'
     var fallback  = type == 'next' ? 'first' : 'last'
@@ -653,7 +653,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
     var data    = $target.data('bs.collapse')
     var option  = data ? 'toggle' : $this.data()
     var parent  = $this.attr('data-parent')
-    var $parent = parent && $(parent)
+    var $parent &&= $(parent)
 
     if (!data || !data.transitioning) {
       if ($parent) $parent.find('[data-toggle="collapse"][data-parent="' + parent + '"]').not($this).addClass('collapsed')
@@ -769,7 +769,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
 
     if (!selector) {
       selector = $this.attr('href')
-      selector = selector && /#[A-Za-z]/.test(selector) && selector.replace(/.*(?=#[^\s]*$)/, '') // strip for ie7
+      selector &&= /#[A-Za-z]/.test(selector) && selector.replace(/.*(?=#[^\s]*$)/, '') // strip for ie7
     }
 
     var $parent = selector && $(selector)
@@ -1024,7 +1024,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
 
   Modal.prototype.checkScrollbar = function () {
     if (document.body.clientWidth >= window.innerWidth) return
-    this.scrollbarWidth = this.scrollbarWidth || this.measureScrollbar()
+    this.scrollbarWidth ||= this.measureScrollbar()
   }
 
   Modal.prototype.setScrollbar = function () {
@@ -1325,8 +1325,8 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
     if (isNaN(marginTop))  marginTop  = 0
     if (isNaN(marginLeft)) marginLeft = 0
 
-    offset.top  = offset.top  + marginTop
-    offset.left = offset.left + marginLeft
+    offset.top += marginTop
+    offset.left += marginLeft
 
     // $.fn.offset doesn't round pixel values
     // so we use setOffset directly with our own function B-0
@@ -1346,7 +1346,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
     var actualHeight = $tip[0].offsetHeight
 
     if (placement == 'top' && actualHeight != height) {
-      offset.top = offset.top + height - actualHeight
+      offset.top += height - actualHeight
     }
 
     var delta = this.getViewportAdjustedDelta(placement, offset, actualWidth, actualHeight)
@@ -1479,11 +1479,11 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
   }
 
   Tooltip.prototype.tip = function () {
-    return (this.$tip = this.$tip || $(this.options.template))
+    return (this.$tip ||= $(this.options.template))
   }
 
   Tooltip.prototype.arrow = function () {
-    return (this.$arrow = this.$arrow || this.tip().find('.tooltip-arrow'))
+    return (this.$arrow ||= this.tip().find('.tooltip-arrow'))
   }
 
   Tooltip.prototype.validate = function () {
@@ -1630,7 +1630,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
   }
 
   Popover.prototype.arrow = function () {
-    return (this.$arrow = this.$arrow || this.tip().find('.arrow'))
+    return (this.$arrow ||= this.tip().find('.arrow'))
   }
 
   Popover.prototype.tip = function () {
@@ -1869,7 +1869,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
 
     if (!selector) {
       selector = $this.attr('href')
-      selector = selector && selector.replace(/.*(?=#[^\s]*$)/, '') // strip for ie7
+      selector &&= selector.replace(/.*(?=#[^\s]*$)/, '') // strip for ie7
     }
 
     if ($this.parent('li').hasClass('active')) return
@@ -2102,7 +2102,7 @@ if (typeof jQuery === 'undefined') { throw new Error('Bootstrap\'s JavaScript re
       var $spy = $(this)
       var data = $spy.data()
 
-      data.offset = data.offset || {}
+      data.offset ||= {}
 
       if (data.offsetBottom) data.offset.bottom = data.offsetBottom
       if (data.offsetTop)    data.offset.top    = data.offsetTop
diff --git a/src/usr/share/rpimonitor/web/js/rpimonitor.status.js b/src/usr/share/rpimonitor/web/js/rpimonitor.status.js
index 5dabf8a..4d3e70e 100644
--- a/src/usr/share/rpimonitor/web/js/rpimonitor.status.js
+++ b/src/usr/share/rpimonitor/web/js/rpimonitor.status.js
@@ -58,15 +58,15 @@ function UpdateStatus () {
       text = "";
       for (var jloop=0; jloop < strips[iloop].line.length; jloop++){
         var line = strips[iloop].line[jloop];
-        text = text + "<p>";
+        text += "<p>";
         try {
-            text = text + eval( line );
+            text += eval( line );
         }
         catch (e) {
-          text = text + "ERROR: " + line + " -> " + e;
+          text += "ERROR: " + line + " -> " + e;
         }
         finally {
-          text = text + "</p>";
+          text += "</p>";
         }
       }
       $("#Text"+iloop).html(text);
diff --git a/src/usr/share/rpimonitor/web/js/rpimonitor.utils.js b/src/usr/share/rpimonitor/web/js/rpimonitor.utils.js
index f30ea47..c947af3 100644
--- a/src/usr/share/rpimonitor/web/js/rpimonitor.utils.js
+++ b/src/usr/share/rpimonitor/web/js/rpimonitor.utils.js
@@ -78,8 +78,8 @@ function Percent(value,total){
 
 function ProgressBar(value, max, warning, danger){
   var percent = ((100 * value ) / max).toFixed(2)
-  var warning = warning || 0
-  var danger = danger || 0
+  var warning ||= 0
+  var danger ||= 0
   var color = ''
   if (danger > warning) {
     if (percent > warning) {
@@ -101,12 +101,12 @@ function ProgressBar(value, max, warning, danger){
 }
 
 function JustGageBar(title, label, min, value, max, width, height, levelColors, warning, critical){
-  width  = width  || 100
-  height = height || 80
-  min = min       || 0
-  max = max       || 1
-  value = value   || 0
-  levelColors = levelColors || percentColors
+  width ||= 100
+  height ||= 80
+  min ||= 0
+  max ||= 1
+  value ||= 0
+  levelColors ||= percentColors
   if (( warning != undefined ) && (critical != undefined)){
     if ( value > critical ) {
       levelColors = [levelColors[2], levelColors[2], levelColors[2]];