I am new to JavaScript, and while learning I got confused. Not sure about title of the question.
Coming straight to point -
var a = 4,
say = console.log,
globalA; // defined global variable's
doSome();
doSomeMore();
function doSome() {
say(a);
var a = 5;
say(++a);
}
function doSomeMore() {
say(a);
}
When I run it, this gives
undefined
6
4
Why is this when doSome executes it has value of a as undefined and not 4 ?
What you're looking for is called hoisting.
It essentially means that when you declare var a in a function this gets moved to the top, and is equal to the following:
function doSome() {
var a; //initialize the variable using hoisting
say(a); //undefined
a = 5;
say(++a);
}
If you remove var in var a = 5 this works as you'd want it to as it then refers to the global a variable:
function doSome() {
say(a); //4
a = 5;
say(++a);
}
change your code
function doSome() {
say(a);
var a = 5;
say(++a);
}
to
function doSome() {
var a = 5;
say(a);
say(++a);
}
