self-invoking-function | 易学教程

JavaScript self-invoking functions [duplicate]

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问题 This question already has answers here : Closed 6 years ago . Possible Duplicate: Difference between (function(){})(); and function(){}(); Are “(function ( ) { } ) ( )” and “(function ( ) { } ( ) )” functionally equal in JavaScript? I just wondered whether there is a difference (regarding the functionality) between these two examples: 1st (function foo() { console.log("bar") })() 2nd (function foo() { console.log("bar") }()) Both seem to work fine ... Thanks! 回答1: They are exactly the same.

Why Don't Variables Reset in a Closure (Javascript)

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I've been trying to learn about closures, but one thing still perplexes me. If I have the following code: var add = (function () { var counter = 0; return function () {return counter += 1;} })(); add(); add(); add(); // Returns "3" If I call add() three times, why dosen't it set counter to zero every time, then return the anonymous funtion that increments counter by one? Does it skip over it once the self-invoking function runs? Sorry if the question seems simple, I'm having a hard time understanding it. Any help would be greatly appreciated. If I call add() three times, why dosen't it set

Different between (function(){})() and (function(){}()) , self invoking anonymous function [duplicate]

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问题 This question already has answers here : Are “(function ( ) { } ) ( )” and “(function ( ) { } ( ) )” functionally equal in JavaScript? [duplicate] (3 answers) Closed 5 years ago . Look at the placement of the parenthesis, is that any different? ( func )( ) (function(){ })(); and ( func( ) ) (function(){ }()); 回答1: Technically the first defines an anonymous function, then calls it, the second defines an anonymous function which calls itself as it's defined. Realistically, they are identical.

need more explanation on w3schools javascript closure example

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I'm trying to understand closures and am looking at the W3Schools javascript tutorial. This is one example they give by making a counter. <body> <p>Counting with a local variable.</p> <button type="button" onclick="myFunction()">Count!</button> <p id="demo">0</p> <script> var add = (function () { var counter = 0; return function () {return counter += 1;} })(); function myFunction(){ document.getElementById("demo").innerHTML = add(); } </script> </body> Example Explained The variable add is assigned the return value of a self-invoking function. The self-invoking function only runs once. It sets

Spring @Transactional Annotation : Self Invocation

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I know when a transactional method is called from inside the same class it wouldn't be run in a transaction. Spring creates a proxy for transactional methods and wraps them in a try-catch block and rolls back if an exception occurs. Consider the following scenario: @Transactional public void saveAB(A a, B b) { saveA(a); saveB(b); } @Transactional public void saveA(A a) { dao.saveA(a); } @Transactional public void saveB(B b) { dao.saveB(b); } Assume saveAB is called from another object and an exception occurred in saveB, so saveA completed successfully but saveB did not. To my knowledge even

What are the differences between these three types of module pattern?

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问题 1)function () { // code here... }(); 2)(function () { // code here... })(); 3)(function () { // code here... }()); What are the differences (especially third variant)? Are they all the same? 回答1: First one gives a syntax error. Second and third versions define a anonymous function and immediately execute it. Second and third versions are also called Immediately Invoked Function Expressions. You might also encounter another version which looks like this. This is equal in functionality to 2nd