var is function scoped

 

var is globally scoped when declared outside of a function. 

 

 

function doWhatEver() {

   if (2>1) {
     var foo = "hello"
   }


   console.log(foo)
}

doWhatEver()

console.log(foo)


// Output: hello​
// Cant find variable: foo

 

 

 

//Numbers
 
var num = 42;
var meaning = "The meaning of life is ";
var life = meaning + num;
 
var otherNum = "15";
var num = 10;
var whaaa = otherNum - num;
 
var likeAnActualNum = parseInt(otherNum, 10); //15
 
var floaty = "1.5";
var likeAnActualDecimal = parseFloat(floaty); //1.5

 

//Strings
 
var foo = "There is no spoon";
var bar = "No, \"really\", " + foo; //No, "really", There is no spoon
var barBetter = "No, \"really\", " + foo.toLowerCase();

 

  

// Undefined
 
var a; // has value of undefined
//console.log(b); // Uncaught ReferenceError: b is not defined
if(b){
    //console.log('a b!');
}​

When a variable is declared but not assigned a value then it is undefined.

 

This might be ... the app will get the value later.

 

// null
 
var a = null; // initialised but with no value
//console.log(a); // null

Null gets assigned to variables ... it indicates an desired missing of a value.