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FirstThe first one(function doSomething(x)) should be part of an object notation.
The second one(var doSomething = function(x){ alert(x);}) is simply creating an anonymous function and assigning it to a variable doSomething, doSomething. So doSomething() will call the function.
youYou may want to What isknow what a Function Declarationfunction declaration and Function Expressionfunction expression is.
A Function Declarationfunction declaration defines a named function variable without requiring variable assignment. Function Declarationsdeclarations occur as standalone constructs and cannot be nested within non-function blocks.
function foo() {
return 3;
}
ECMA 5 (13.0) defines the syntax as
function Identifier ( FormalParameterListopt ) { FunctionBody }
inIn above condition the function name is visible within it’sits scope and the scope of it’sits parent (otherwise it would be unreachable).
andAnd in a function expression
A Function Expressionfunction expression defines a function as a part of a larger expression syntax (typically a variable assignment ). Functions defined via Functions Expressionsfunctions expressions can be named or anonymous. Function Expressionsexpressions should not start with "function".
//anonymous Anonymous function expression
var a = function() {
return 3;
}
//named Named function expression
var a = function foo() {
return 3;
}
//self Self-invoking function expression
(function foo() {
alert("hello!");
})();
ECMA 5 (13.0) defines the syntax as
function Identifieropt ( FormalParameterListopt ) { FunctionBody }
First one(function doSomething(x)) should be part of an object notation.
The second one(var doSomething = function(x){ alert(x);}) is simply creating an anonymous function and assigning it to a variable doSomething . So doSomething() will call the function.
you may want to What is a Function Declaration and Function Expression
A Function Declaration defines a named function variable without requiring variable assignment. Function Declarations occur as standalone constructs and cannot be nested within non-function blocks.
function foo() {
return 3;
}
ECMA 5 (13.0) defines the syntax as
function Identifier ( FormalParameterListopt ) { FunctionBody }
in above condition the function name is visible within it’s scope and the scope of it’s parent (otherwise it would be unreachable)
and in function expression
A Function Expression defines a function as a part of a larger expression syntax (typically a variable assignment ). Functions defined via Functions Expressions can be named or anonymous. Function Expressions should not start with "function"
//anonymous function expression
var a = function() {
return 3;
}
//named function expression
var a = function foo() {
return 3;
}
//self invoking function expression
(function foo() {
alert("hello!");
})();
ECMA 5 (13.0) defines the syntax as
function Identifieropt ( FormalParameterListopt ) { FunctionBody }
The first one(function doSomething(x)) should be part of an object notation.
The second one(var doSomething = function(x){ alert(x);}) is simply creating an anonymous function and assigning it to a variable, doSomething. So doSomething() will call the function.
You may want to know what a function declaration and function expression is.
A function declaration defines a named function variable without requiring variable assignment. Function declarations occur as standalone constructs and cannot be nested within non-function blocks.
function foo() {
return 3;
}
ECMA 5 (13.0) defines the syntax as
function Identifier ( FormalParameterListopt ) { FunctionBody }
In above condition the function name is visible within its scope and the scope of its parent (otherwise it would be unreachable).
And in a function expression
A function expression defines a function as a part of a larger expression syntax (typically a variable assignment ). Functions defined via functions expressions can be named or anonymous. Function expressions should not start with "function".
// Anonymous function expression
var a = function() {
return 3;
}
// Named function expression
var a = function foo() {
return 3;
}
// Self-invoking function expression
(function foo() {
alert("hello!");
})();
ECMA 5 (13.0) defines the syntax as
function Identifieropt ( FormalParameterListopt ) { FunctionBody }
First one(function doSomething(x)) should be part of an object notation.
The second one(var doSomething = function(x){ alert(x);}) is simply creating an anonymous function and assigning it to a variable doSomething . So doSomething() will call the function.
you may want to What is a Function Declaration and Function Expression
A Function Declaration defines a named function variable without requiring variable assignment. Function Declarations occur as standalone constructs and cannot be nested within non-function blocks.
function foo() {
return 3;
}
ECMA 5 (13.0) defines the syntax as
function Identifier ( FormalParameterListopt ) { FunctionBody }
in above condition the function name is visible within it’s scope and the scope of it’s parent (otherwise it would be unreachable)
and in function expression
A Function Expression defines a function as a part of a larger expression syntax (typically a variable assignment ). Functions defined via Functions Expressions can be named or anonymous. Function Expressions should not start with "function"
//anonymous function expression
var a = function() {
return 3;
}
//named function expression
var a = function foo() {
return 3;
}
//self invoking function expression
(function foo() {
alert("hello!");
})();
ECMA 5 (13.0) defines the syntax as
function Identifieropt ( FormalParameterListopt ) { FunctionBody }