Execute function immediately

First, JS immediately execute the function of the wording



Way 1, the last parenthesis

(function () {alert (1);} ());


Mode 2, function outside parentheses

(function () {alert (1);}) ();


Mode 3, function front plus operator, common is! with void

!function () {alert (1);} ();
void function () {alert (2);} ();


Second, immediately execute the parameters of the function

Arguments can be passed to an immediate execution function, such as

(function (who, when) {
    Console.log ("I met" + Who + ' on ' + when);
} ("Joe Black", New Date ()));

Remember:

1, immediately inside the function can access external variables, so in many cases, we do not need to pass parameters. such as: jquery window arguments, if not passed in. The interior is also available for direct use.

2. Usually you should not pass too many functions to the immediate execution function, because it will soon become a burden--in order to understand how the code works, you have to scroll the source code up and down frequently.



Third, immediately execute the return value of the function

Like any other function, an immediate execution function can return a value and can be copied to other variables, such as


var result = (function () {
return 2 + 2;
}());


var result = (function () {
return 2 + 2;
})();

Execute function immediately