function overloading in JavaScript deep understanding of _javascript techniques

There is a special data type---function type in JavaScript, and every function of JavaScript is an instance of a function type. Because a function is an object, the function name is actually a pointer to a function object and is not bound to a function.

<pre name= "code" class= "HTML" >function sum (num1,num2) 
{return 
num1 +num2; 
} 

Alert (sum (10,10)); 
var other = sum; 
Alert (Other (10,10)); 
sum = null; 
Alert (Other (10,10)); 20

The function name as a pointer to a function helps to understand why there is no concept of a function overload in ECMAScript

function sum (NUM1) 
{return 
num1 +100; 
} 
function sum (NUM1) 
{return 
num1 +200; 
} 
Alert (sum (200)); 400

Although two functions with the same name are declared, the following function overrides the previous function, which is equivalent to the code below

function sum (NUM1) 
{return 
num1 +100; 
} 
sum = function (NUM1) 
{return 
num1 +200; 
} 
Alert (sum (200)); 400

When you create the second function, you actually overwrite the first function variable of the reference. Sum