Difference between declaring variable

Question

What is the difference between how a variable can be declared?

a = 5;

and

var a = 5;

Is there any relation to the definition of scope?

+4

kamal May 17, '15 at 16:15

4 answers

var awill create a local variable. Another will create and / or set a global variable.

In most cases, you are better off creating local variables unless you need to create a global variable.

+2

manojlds May 17 '15 at 16:17

, - .

var , .

, , .

+1

Guffa 17 '15 16:30

a = 5;

, , ( , , ).

var a = 5;

. , , .

, var a = 5 . .

function() {
    doSomestuff();
    a = 4;
    var a = 5;
    doOtherStuff();
}

function() {
    var a = 5;
    doSomestuff();
    a = 4;
    doOtherStuff();
}

, , a = 5. var.

It is worth it to turn your undetectable errors into obvious errors.

+1

Jonny May 17 '15 at 16:33

Himanshu tanwar · Accepted Answer · 2015-05-17T16:19:14+0000

a = 5 will declare a global variable from any scope. var a = 5 will declare a variable in the declared scope.

 a = 5;    //global variable
 var b = 6; // global variable
 function foo(){
  var c = 7; //local variable
  d = 9; //global variable
  }