keep (function(){...})()

The form (function(){...})() is a function literal that is executed immediately. What this means is that you have defined a function and you are calling it immediately. This form is useful for information hiding and encapsulation since anything you define inside that function remains local to that function and inaccessible from the outside world.
meedan · Aug 16, 2023 · a88d01e · a88d01e
1 parent 8499ad0
commit a88d01e
Showing 1 changed file with 74 additions and 72 deletions.
diff --git a/public/javascripts/embed.js b/public/javascripts/embed.js
@@ -3,78 +3,80 @@
 // This happens on the child window
 var Pender = {};
 
-'use strict';
-
-// Alert parent window when the height changes
-var htmlHeight = 0;
-if (!Pender.id) {
-  Pender.id = md5(document.location.search.replace(/^\?url=/, ''));
-}
-var checkHTMLHeight = function() {
-  var height = document.getElementsByTagName('BODY')[0].offsetHeight;
-  if (height !== htmlHeight) {
-    htmlHeight = height;
-    window.parent.postMessage(['setHeight', Pender.id, htmlHeight].join(';'), '*');
-  }
-  setTimeout(checkHTMLHeight, 100);
-};
-
-var isElementOnViewPort = function(el, data) {
-  var rect = el.getBoundingClientRect(),
-      h = data[0], w = data[1], tp = data[2], left = data[3];
-
-  var offset = 500;
-
-  return (
-    rect.top + tp >= 0 &&
-    rect.left + left >= 0 &&
-    rect.bottom + tp <= (h + offset) &&
-    rect.right + left <= w
-  );
-};
-
-var lazyLoad = function(data) {
-  // Nothing to do right now
-};
-
-var messageCallback = function(e) {
-  var data = e.data.toString().split(';'),
-      type = data.shift();
-
-  for (var i = 0; i < data.length; i++) {
-    data[i] = parseInt(data[i], 10);
-  }
-
-  switch (type) {
-    // Lazy load
-    case 'lazyLoad':
-      lazyLoad(data);
-      break;
+(function() {
+  'use strict';
+
+  // Alert parent window when the height changes
+  var htmlHeight = 0;
+  if (!Pender.id) {
+    Pender.id = md5(document.location.search.replace(/^\?url=/, ''));
   }
-};
-
-var resizeOrScrollCallback = function() {
-  var h = window.innerHeight || document.documentElement.clientHeight,
-      w = window.innerWidth || document.documentElement.clientWidth,
-      data = [h, w, 0, 0, 0, 0];
-  lazyLoad(data);
-};
-
-if (!window.addEventListener) {
-  window.attachEvent('onmessage', messageCallback);
-  if (window === window.parent) {
-    window.attachEvent('onscroll', resizeOrScrollCallback);
-    window.attachEvent('onresize', resizeOrScrollCallback);
-    window.attachEvent('onload', resizeOrScrollCallback);
+  var checkHTMLHeight = function() {
+    var height = document.getElementsByTagName('BODY')[0].offsetHeight;
+    if (height !== htmlHeight) {
+      htmlHeight = height;
+      window.parent.postMessage(['setHeight', Pender.id, htmlHeight].join(';'), '*');
+    }
+    setTimeout(checkHTMLHeight, 100);
+  };
+
+  var isElementOnViewPort = function(el, data) {
+    var rect = el.getBoundingClientRect(),
+        h = data[0], w = data[1], tp = data[2], left = data[3];
+
+    var offset = 500;
+
+    return (
+      rect.top + tp >= 0 &&
+      rect.left + left >= 0 &&
+      rect.bottom + tp <= (h + offset) &&
+      rect.right + left <= w
+    );
+  };
+
+  var lazyLoad = function(data) {
+    // Nothing to do right now
+  };
+
+  var messageCallback = function(e) {
+    var data = e.data.toString().split(';'),
+        type = data.shift();
+
+    for (var i = 0; i < data.length; i++) {
+      data[i] = parseInt(data[i], 10);
+    }
+
+    switch (type) {
+      // Lazy load
+      case 'lazyLoad':
+        lazyLoad(data);
+        break;
+    }
+  };
+
+  var resizeOrScrollCallback = function() {
+    var h = window.innerHeight || document.documentElement.clientHeight,
+        w = window.innerWidth || document.documentElement.clientWidth,
+        data = [h, w, 0, 0, 0, 0];
+    lazyLoad(data);
+  };
+
+  if (!window.addEventListener) {
+    window.attachEvent('onmessage', messageCallback);
+    if (window === window.parent) {
+      window.attachEvent('onscroll', resizeOrScrollCallback);
+      window.attachEvent('onresize', resizeOrScrollCallback);
+      window.attachEvent('onload', resizeOrScrollCallback);
+    }
+    window.attachEvent('onload', checkHTMLHeight);
   }
-  window.attachEvent('onload', checkHTMLHeight);
-}
-else {
-  window.addEventListener('message', messageCallback, false);
-  if (window === window.parent) {
-    window.addEventListener('scroll', resizeOrScrollCallback, false);
-    window.addEventListener('resize', resizeOrScrollCallback, false);
-    window.addEventListener('load', resizeOrScrollCallback, false);
+  else {
+    window.addEventListener('message', messageCallback, false);
+    if (window === window.parent) {
+      window.addEventListener('scroll', resizeOrScrollCallback, false);
+      window.addEventListener('resize', resizeOrScrollCallback, false);
+      window.addEventListener('load', resizeOrScrollCallback, false);
+    }
+    window.addEventListener('load', checkHTMLHeight, false);
   }
-  window.addEventListener('load', checkHTMLHeight, false);
-}
+}())