Create 14-Functions.md

Author: HariAcidReign

Notes/14-Functions.md

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+# Episode 14 : First class and Anonymous functions
+
+(there is no Episode 13 idk why lol)
+
+#### Function statement : Just your normal function definition 
+
+```
+function a() {
+  console.log("a called");
+}
+a();
+
+```
+
+#### Function Expression : Assigning a function to a variable. Function acts like a value
+
+```
+var b = function() {
+  console.log("b called");
+}
+b();
+
+```
+
+**Difference btw function statement and expression is Hoisting**
+- You can put "a();" before "function a()" and it will still work. But putting "b();" before "var b = function()" throws a typeError.
+- Why? During mem creation phase a is created in memory and function assigned to a. But b is created like a variable (b:undefined) and until code reaches the function() 
+part, it is still undefined. So it cannot be called.
+
+#### Function Declaration : Exactly same as function statement
+
+#### Anonymous Function : A function without a name
+- They don't have their own identity. So an anony function without code inside it results in an error. 
+- Anony functions are used when functions are used as values eg. the code sample for function expression above
+
+#### Named Function Expression : Same as Function Expression but function has a name instead of being anonymous
+```
+var b = function xyz() {
+  console.log("b called");
+}
+b(); // prints "b called" properly
+xyz(); // Throws ReferenceError:xyz is not defined.
+
+```
+> xyz function is not created in global scope. So it can't be called.
+
+#### Parameters vs Arguments 
+```
+var b = function(param1, param2) {  // labels/identifiers that get the arg values 
+  console.log("b called");
+}
+b(arg1, arg2); // arguments - values passed inside function call
+
+```
+#### First Class Function aka First Class Citizens
+- You can pass functions inside a function as arguments(WOW!)
+
+```
+var b = function(param1) {
+  console.log(param1); // prints " f() {} "
+}
+b(function(){
+  
+});
+
+this can also be done:
+
+var b = function(param1) {
+  console.log(param1);
+}
+function xyz(){
+
+}
+b(xyz); // same thing as prev code
+
+you can return a function from a function:
+
+var b = function(param1) {
+  return function() {
+  
+  }  
+}
+console.log(b()); //we log the entire fun within b. 
+
+```
+#### Arrow Functions (latest in ES6 (ECMAScript 2015)
+