Detailed explanation of the calling and writing methods of anonymous functions in Javascript (various types)_javascript skills

There are many ways to define functions in Javascript, and function literals are one of them. For example, var fun = function(){}, if function is not assigned to fun, then it is an anonymous function. Okay, let's see how the anonymous function is called.

Method 1, call the function and get the return value. The coercion operator causes function calls to execute

(function(x,y){
alert(x+y);
return x+y;
}(3,4)); 

Method 2, call the function and get the return value. Force the function to be executed directly and then return a reference, and then the reference is called and executed

(function(x,y){
alert(x+y);
return x+y;
})(3,4); 

This method is also a favorite calling method used by many libraries, such as jQuery and Mootools.

Method 3, use void

void function(x) {
x = x-1;
alert(x);
}(9);

Method 4, use -/+ operator

-function(x,y){
alert(x+y);
return x+y;
}(3,4);
+function(x,y){
alert(x+y);
return x+y;
}(3,4);
--function(x,y){
alert(x+y);
return x+y;
}(3,4);
++function(x,y){
alert(x+y);
return x+y;
}(3,4); 

Method 5, use the tilde (~)

~function(x, y) {
alert(x+y);
return x+y;
}(3, 4); 

Method 6, anonymous function execution is placed within square brackets

[function(){
console.log(this) // 浏览器得控制台输出window
}(this)] 

Method 7, add typeof

before the anonymous function

typeof function(){
console.log(this) // 浏览器得控制台输出window
}(this) 

Method 8, add delete

before the anonymous function

delete function(){
console.log(this) // 浏览器得控制台输出window
}(this) 

Method 9, add void

before the anonymous function

void function(){
console.log(this) // 浏览器得控制台输出window
}(this) 

Method 10, use new method to pass parameters

new function(win){
console.log(win) // window
}(this) 

Method 11, use new, do not pass parameters

new function(){
console.log(this) // 这里的this就不是window了
} 

Method 12, comma operator

 function(){
console.log(this) // window
}(); 

Mode 13, bitwise XOR operator

^function(){
console.log(this) // window
}(); 

Method 14, comparison operator

function(){
console.log(this) // window
}(); 

Finally look at the wrong calling method

function(x,y){
alert(x+y);
return x+y;
}(3,4); 

N ways of writing anonymous functions are as follows

Anonymous functions have no actual names and no pointers. How to execute them?

About how to write anonymous functions, it’s very divergent~

The

+ sign converts a function declaration into a function expression. Summarize it

Most common usage:

The code is as follows:

(function() { 
alert('water'); 
})(); 

Of course, you can also take parameters:

The code is as follows:

(function(o) { 
alert(o); 
})('water'); 

Want to use chain calls of anonymous functions? Very simple:

The code is as follows:

(function(o) { 
console.log(o); 
return arguments.callee; 
})('water')('down'); 

We all know the common anonymous functions, let’s take a look at the uncommon ones:

The code is as follows:

~(function(){ 
alert('water'); 
})();//写法有点酷~ 

The code is as follows:

void function(){ 
alert('water'); 
}();//据说效率最高~ 

The code is as follows:

+function(){ 
alert('water'); 
}(); 

The code is as follows:

-function(){ 
alert('water'); 
}();

The code is as follows:

~function(){ 
alert('water'); 
}();

The code is as follows:

!function(){ 
alert('water'); 
}(); 

The code is as follows:

(function(){ 
alert('water'); 
}());//有点强制执行的味道~

The above has shared with you how to call and write anonymous functions in Javascript. I hope it will be helpful to you.