JavaScript immediate execution function usage analysis

We know that in general, a function must be called before it can be executed. As shown below, we define a function and call it.

function fn(){
    console.log(1);
    }
    fn();

The print result is:

If we don't call it, the results we print will never be displayed.
So here we will mention our immediately executed function. The so-called immediately executed function is a function that can be executed immediately without being called.

There are two most common ways to write an immediate execution function:

• (function(){})()
• (function(){}())

For example:

 (function fn(){
            console.log(2);
        })()

The print result is:

Printing successful.

The second parentheses in the immediately executed function are equivalent to calling the function. We can also pass parameters to the immediately executed function. Write the parameters we want to pass in the second () as actual parameters.

as follows:

 (function fn(a,b){
    console.log('a+b='+a+b);
 })(1,2)

The print result is:

The second method of using the immediately executed function is basically similar to the first one, so I will not go into details here.
It should be noted that if there are multiple immediately executed functions, they need to be separated by commas, otherwise an error will be reported. At the same time, in the immediately executed function, it can also be written in the form of an anonymous function.

So what are the functions or benefits of executing functions immediately?

Its biggest function is to create an independent scope. We know that there is no concept of private scope in javascript . If some variables are declared in the global or local scope in a project developed by multiple people, they may be accidentally overwritten by other people with variables of the same name. However, the variables in the immediately executed function are all local variables, and there will be no naming conflicts.

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