Function declaration and expression in js, js function declaration expression

Function declaration and expression in js, js function declaration expression
// Function declaration: function name (){}


// Function expression: function name (writable or not) () {}: anonymous function expression


// Function aaa () {}: function declaration


// Var a = function aaa () {}: name function expression
// Var a = function () {}: anonymous function expression


(Function aaa () {}): Expression
~ Function aaa (){}
-Function aaa (){}
+ Function aaa (){}

! Function aaa (){}

/Differences:
// 1. The function expression can be executed directly in parentheses, but the function declaration is not.
// 2. The function declaration can be parsed in advance.




// Function aaa () {alert (1 );}();


// Var a = function aaa () {alert (1 );}();


//~ Function aaa () {alert (1 )}();




/* If (true ){
Function aaa (){
Alert (1 );
}
}
Else {
Function aaa (){
Alert (2 );
}
}


Aaa ();*/




If (true ){
Var a = function aaa (){
Alert (1 );
}
}
Else {
Var a = function aaa (){
Alert (2 );
}
}


A ();

/*
Var a = function aaa (){
Alert (1 );
Alert (typeof aaa); // can be found internally
}


// ();


Aaa (); // cannot be found outside */




(Function aaa () {alert (1 )})


Aaa ();

Function aaa (){


Return bbb ();


}


/* Function bbb (){
Debugger;
}*/


Var bbb = (function bbb (){


Return function (){
Debugger;
}

})();


Aaa ();

Copyright Disclaimer: This article is an original article by the blogger and cannot be reproduced without the permission of the blogger.