var
A variable declared anywhere inside a function using "var" has function scope.
A variable declared using "var" is hoisted.
A variable declared using "var" can be accessed before it has been declared because the hoisting initialises it to the value "undefined".
var variables are initialized with a value of undefined.
var variables can be used before they have been declared.
var variables can be re-declared within the scope.
function myFunction() {
var x = 100;
if (true) {
var x = 200;
}
console.log(x); // x is 200
}
This is because x has a function scope and does not have block scope.
Global scope
If the var keyword is omitted and a value is just assigned to a variable then it will have 'global scope'.
For global scope just leave off the var
var Data = "smith";
You can use strict mode to prevent this
Warning - Same Names
The 'var' keyword will let you redeclare a variable with the same name in the same scope.
let' and 'const' will not allow this.
Warning - Inside a For Loop
Declaring a variable with 'var' inside a for loop can be accessed from outside the for loop, infact from anywhere in that function.
Warning - Last Value that has been assigned
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