javascript - How to understand this js code?

Question

My doubt is what do the parentheses surrounding this function mean, closure?
Then (1) at the end of the method is to bring parameter 1 into this anonymous method?
Does the lexicon of these parentheses mean execution or isolation method?

Answer 1

It means to execute immediately, pass in parameter 1

(function(x){

})(1)

Answer 2

This is an immediate execution function. The immediate execution function constructs a function scope, which can play a role in isolation and avoid polluting the global scope. Passing in 1 is the incoming parameter. The immediate execution function can be used to solve closure problems. . But it is not directly related to closure.

Answer 3

Anonymous functions do not have a function name and cannot be called. When the function declaration is enclosed in parentheses, it is no longer a function declaration, but a function expression. Adding () after it means executing the function immediately. 1 is the parameter, which is received by x inside.
You can understand it as

var foo = function(x){
    delete x;
    return x;
};
foo(1);