A self invoking anonymous function expression

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invokinganonymousfunction
90%

You can also pass parameters to the self-invoking functions. It is a commonly used practice to pass references to global objects:,There few small (but important) syntax variations. Douglas Crockford’s JSLint offers the correct declaration for self-invoking functions as:,There are a lot of interesting things in the syntax of JavaScript, one of which is the definition of self-executing (self-invoking) functions. Here’s how we can defined such function:,Usually the module pattern is implemented using self-invoking functions. In the module pattern, we keep the reference to the function’s returned object. In such case we consider the return value as the public API of the module:

(function() {
   // body of the function
}());
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88%

A self-invoking expression is invoked (started) automatically, without being called.,Function expressions can be made "self-invoking".,JavaScript functions can be used in expressions:,Functions defined using an expression are not hoisted.


JavaScript functions are defined with the function keyword.

function
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72%

this is Immediately Invoked Function Expression. So when your javascript file invoked from HTML this function called immediately.,Actually, the above function will be treated as function expression without a name.,So lets look at our code again, with some self-executing syntax:,A self-invoking expression is invoked (started) automatically, without being called. A self-invoking expression is invoked right after its created. This is basically used for avoiding naming conflict as well as for achieving encapsulation. The variables or declared objects are not accessible outside this function. For avoiding the problems of minimization(filename.min) always use self executed function.

(function() {
   var foo = 3;
   console.log(foo);
})();

console.log(foo);
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65%

A self-invoking (also called self-executing) function is a nameless (anonymous) function that is invoked immediately after its definition. ,Self-invoking functions are useful for initialization tasks and for one-time code executions, without the need of creating global variables.,Parameters can also be passed to self-invoking functions as shown in the example below.,A self-invoking function can have variables and methods but they cannot be accessed from outside of it. To access them, the global window object has to be passed as a parameter.

(function() {
   console.log(Math.PI);
})();
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75%

A self-invoking function is a nameless (anonymous) function that is invoked immediately after its definition.,An anonymous function is enclosed inside a set of parentheses followed by another set of parentheses (), which does the execution.,You can also pass parameters to the self-invoking functions. It is a commonly used practice to pass references to global objects:,Self-invoking functions are useful for initialization tasks. For example, if we have a web page in which we want to attach event listeners to DOM elements and other initialization work, self-invoking functions would be the best tool for the job!

In JavaScript, functions are usually declared like this:

function myFunctionName(parameters) { //some code that does something.}

This is called a declared function. Declared functions are not executed immediately. Basically, declared functions are saved for you to use them somewhere else so this means it’s not called upon or “invoked” until you call it like this:

myFunctionName("Function parameters");
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40%

As these functions are unnamed or anonymous, expression of the function is immediately invoked even without using any identifier or closure and not spoiling the scope.,These anonymous functions are arguments passed to higher-order functions that needs to return a function. If the function is used only once, using a self Invoking function is easier as it is light weighted syntactically compared to the named function.,These functions are called as Immediately Invoked Function Expressions, as IIFE or Self Executing functions. The purpose of wrapping these functions is to control the visibility of its members. You might be thinking why we would ever need to use these self-invoking functions. So, let us dig deeper into it.,Even though you might find slight variations here, the content of the function is the same and both variations are executed immediately. As soon the function is defined, it will be immediately invoked. This is useful in initialization, adding event listeners, etc. In jQuery, instead of using document. ready, a self-invoked function was used.

(function() {
// body of the function
})();

(function() {
   // body of the function
})();
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In JavaScript, the functions wrapped with parenthesis are called “Immediately Invoked Function Expressions" or "Self Executing Functions.,The purpose of wrapping is to the namespace and control the visibility of member functions. It wraps the code inside a function scope and decreases clashing with other libraries. This is what we call Immediately Invoked Function Expression (IIFE) or Self Executing Anonymous Function.,Invoking functions with call() and apply() in JavaScript,In addition, the next pair, i.e. the second pair of parentheses continues the operation. It calls the function, which resulted from the expression above.

Here’s the syntax −

(function() {
   // code
})();
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60%

The self-executing anonymous function is a special function which is invoked right after it is defined. There is no need to call this function anywhere in the script. This type of function has no name and hence it is called an anonymous function. The function has a trailing set of parenthesis. The parameters for this function could be passed in the parenthesis.,Accessing a variable from outside the anonymous function: This example shows that accessing the date object from outside the anonymous function results in an error.,Allowing access to one variable to outside the function: This example shows that the date variable could be made available outside the function by making it global.,What is the purpose of self executing function in JavaScript?

Syntax:

(function(parameters) {
   // Function body
})(parameters);
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