Function definition of javascript study notes_javascript skills

Function declaration

function funname( 参数 ){

　　...执行的代码

}

The declarative function will not be executed immediately. It will only be executed after we call it: funname();

* Semicolon is used to separate executable JavaScript statements. Since the function declaration is not an executable statement, it does not end with a semicolon.

Function expression

var x = function( 参数 ){

　　...执行的代码块

};

The function defined by the function expression is actually an anonymous function (this function has no name and is stored directly in a variable)

* A semicolon is required at the end of the function expression because it is an execution statement.

Function constructor

Copy code The code is as follows:

var myFunction = new Function( "a" , "b" , "return a * b" );

Call a function and assign it to a variable:

Copy code The code is as follows:

var x = myFunction( 4 , 3 ); // x = 12;

In actual production, it is not recommended to use constructors to define functions. We can rewrite the above example as:

Copy code The code is as follows:

var myFunction = function( a,b ){ return a * b };
var x = myFunction( 4 , 3 ); // x = 12;

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