Differences

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--- javascript [2021/06/05 17:29] – admin
+++ javascript [2021/07/23 14:52] (current) – admin
@@ Line 8: / Line 8: @@
 ## Basic
+### Datatype
+```
+var length = 16;                               // Number
+var lastName = "Johnson";                      // String
+var x = {firstName:"John", lastName:"Doe"};    // Object
+```
 ### Object
 Create an object with 3 properties:
-```
+```javascript
 var object = {
   ID: 1,
   "name": "Tom",
-  subobject: {
+  grade: {
+    math: 94
+    physics:89
   }
-};
+  // When a function is used as an object property, it is called a method
+  sum: function(a,b){
+    return a+b;
+  }
+}
 ```
-Use dot ```.``` or bracket ```[]``` to access properties
+Use dot ```.``` or bracket ```[]``` to access or create properties
 ```javascript
 object.ID = object.ID + 1;
 object["ID"] = object["ID"] + 1;
-// Bracket can be used to create new properties
+object.grade.math = 100;
+// Method can be called in the same way
+object.sum(1, 2);
+// Create new properties or methods in the same way
 object[name + "-full"] = "Tom Hanks";
+object.minus = function(a,b) {
+  return a-b;
+};
 ```
+### Question Mark "?"
+Three use of question mark: [[https://www.freecodecamp.org/news/how-the-question-mark-works-in-javascript/|Link]]
 ## jQuery
@@ Line 106: / Line 130: @@
 ```
-#### Create your own functions (plugins)
+#### jQuery plugins
 Example: to create a plugin that makes text within a set of retrieved elements green. All we have to do is add a function called greenify to ```$.fn``` and it will be available just like any other jQuery object method.
@@ Line 139: / Line 163: @@
 ```javascript
 $("#p1").css("color", "red").slideUp(2000).slideDown(2000);
+```
+#### Normal javascript function in jQuery?
+You might want to just have a function in jQuery to use the query features. However it could not be called outside of the jQuery namespace. Here's an example:
+```javascript
+$(document).ready( function () {
+    var MyBlah = function(blah) { alert(blah);  };
+    MyBlah("Hello this works") // Inside the anonymous function we are cool.
+ });
+MyBlah("Oops") //This throws a JavaScript error (MyBlah is not a function)
+```
+This is (sometimes) a desirable behavior since we do not pollute the global namespace, so if your function does not need to be called from other part of your code, this is the way to go.
+Declaring it outside the anonymous function places it in the global namespace, and it's accessible from everywhere.
+If you want to call it anywhere, use the `$.` namespace:
+```javascript
+$(document).ready( function () {
+    $.MyBlah = function(blah) { alert(blah);  };
+    MyBlah("Hello this works") // Inside the anonymous function we are cool.
+ });
+$.MyBlah("Oops") //This throws a JavaScript error (MyBlah is not a function)
 ```