Expression and Statement are very important component in javascript language.
Expression : Expression always create value and can be set wherever a value is expected like function arguments or value assigning in a variable.
val
2+val
fun("3","2")
Statement : In javascript statement perform action. Loop and if statement are example of statement. Javascript wherever expect statement you can put expression but you can not put statement where expression expect .
This is statement
if(true){}
This is expression(function as expression)
function(){return true;}
So you can put expression in where statement is require
if(function(){return true;}){}
But you can not put statement in where expression is require
function(if(true){}){};
In next article i will describe why this two things are very important.