Three ways to define functions in JavaScript

This article mainly introduces relevant information to you about the three implementation methods of defining functions in JavaScript. I hope that through this article you can master the three methods of defining functions. Friends in need can refer to it. I hope it can help you.

Three implementation methods of JavaScript defined functions

【1】Normal method

function print(msg){
  document.write(msg);
}

Several ways to call a function:

Function name (parameter 1 passed to the function, parameter 2 passed to the function,...)

Variable = function name (parameter 1 passed to the function, parameter 2 passed to the function,...)

For function calls with return values, the returned results can also be used directly in the program, For example: alert("sum=" + square(2,3));

A function that does not specify any function value returns undefined.

【2】Constructor method new Function();

   //构造函数方式定义javascript函数 注意Function中的F大写
    var add=new Function('a','b','return a+b;');


    //调用上面定义的add函数
    var sum=add(3,4);
    alert(sum);

Note: accept any number of string parameters, the last parameter is function body.

If only one string is passed, it is the function body.

[3] Function literal definition function

 //使用函数直接量的方式定义函数
   var result=function(a,b){return a+b;}
 
   //调用使用函数直接量定义的函数
   var sum=result(7,8);
   alert(sum);

Note: Function literal is an expression, which can define anonymous functions.

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