• Scope in JavaScript is a hugely important concept.
• Understanding how scope works will help you make design decisions when writing your code.
• JavaScript has two scopes. Global and Local.

• Global scoped variables are available everywhere.
• Can get confusing having lots of global variables.
• Might be easier for small projects but will give you headaches for bigger projects.
• Can be overridden when a local variable has the same name.
• This is a bad practice. Keep your global & local variables named differently.
• Normally only objects & functions will be global, not primitives like numbers and booleans.
• There is ONE global scope that everything shares.
• In the browser, this is the Window object. In node, or other platforms, it's something else.

• Local scopes designated by curly braces.
• However, curly braces alone do not create a local scope.
• Objects & Functions create a local scope.
• Variables in different local scopes can have the same name.
• This is useful for common variables like counters, parameters, etc.
• Global scoped variables are available in local scopes.
• A variable declared in one local scope is not accessible in another local scope.
• This is not a best practice. You want to use parameters to access variables from outside of a local scope.

• Allow you to create reproducible Objects
• Can use instanceof to check Object type
• Perfect for Objects that hold state
• Enables use of the 'this' keyword inside a function
• Used when you are creating a multiple objects that will have the same structure but different contents.

//constructor declarationfunction CustomObject() {};//using constructor to create an objectvar myObj = new CustomObject();myObj instanceof CustomObject;// > true

 //declare constructor function function MyObject() { } //create object with constructor var myObj = new MyObject();

 //constructor declaration with constructor arguments function MyObject(dataObj) {     this.data = dataObj; } //use the arguments like this: var myObj = new MyObject({items : 4}); console.log(myObj.data.items); // > 4

 function MyObject() {   return {     items : 3,     count : function(num) {        console.log(num);     }   } }