airbr · August 30, 2020 03:17 · Aug 30, 2020
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,54 @@
+///////////////////////////////////
+// 5. More about Objects; Constructors and Prototypes
+
+// Objects can contain functions.
+var myObj = {
+    myFunc: function(){
+        return "Hello world!";
+    }
+};
+myObj.myFunc(); // = "Hello world!"
+
+// When functions attached to an object are called, they can access the object
+// they're attached to using the `this` keyword.
+myObj = {
+    myString: "Hello world!",
+    myFunc: function(){
+        return this.myString;
+    }
+};
+myObj.myFunc(); // = "Hello world!"
+
+// What this is set to has to do with how the function is called, not where
+// it's defined. So, our function doesn't work if it isn't called in the
+// context of the object.
+var myFunc = myObj.myFunc;
+myFunc(); // = undefined
+
+// Inversely, a function can be assigned to the object and gain access to it
+// through `this`, even if it wasn't attached when it was defined.
+var myOtherFunc = function(){
+    return this.myString.toUpperCase();
+};
+myObj.myOtherFunc = myOtherFunc;
+myObj.myOtherFunc(); // = "HELLO WORLD!"
+
+// We can also specify a context for a function to execute in when we invoke it
+// using `call` or `apply`.
+
+var anotherFunc = function(s){
+    return this.myString + s;
+};
+anotherFunc.call(myObj, " And Hello Moon!"); // = "Hello World! And Hello Moon!"
+
+// The `apply` function is nearly identical, but takes an array for an argument
+// list.
+
+anotherFunc.apply(myObj, [" And Hello Sun!"]); // = "Hello World! And Hello Sun!"
+
+// This is useful when working with a function that accepts a sequence of
+// arguments and you want to pass an array.
+
+Math.min(42, 6, 27); // = 6
+Math.min([42, 6, 27]); // = NaN (uh-oh!)
+Math.min.apply(Math, [42, 6, 27]); // = 6