Three implementation methods for defining functions in JavaScript

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Three implementation methods of defining functions in JavaScript

[1]Normal method

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

How to call functions One way:

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 return can also be used directly in the program The result, for example: alert("sum=" + square(2,3));

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

【2】ConstructorMethod 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 the function body.

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

【3】Function literal defines 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 function

The above is all the content of this article. I hope it can help everyone learn JavaScript! !

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