谁能帮我解释一下js的这种写法是啥意思？UUID.prototype.createUUID = function()

Posted 2023-03-20

利用JS生成32位的UUID（源码）
创建 UUID.js 文件, 然后复制以下内容:

// On creation of a UUID object, set it's initial value
function UUID()
this.id = this.createUUID();


// When asked what this Object is, lie and return it's value
UUID.prototype.valueOf = function() return this.id; ;
UUID.prototype.toString = function() return this.id; ;

//
// INSTANCE SPECIFIC METHODS
//
UUID.prototype.createUUID = function()
//
// Loose interpretation of the specification DCE 1.1: Remote Procedure Call
// since javascript doesn't allow access to internal systems, the last 48 bits
// of the node section is made up using a series of random numbers (6 octets long).
//
var dg = new Date(1582, 10, 15, 0, 0, 0, 0);
var dc = new Date();
var t = dc.getTime() - dg.getTime();
var tl = UUID.getIntegerBits(t,0,31);
var tm = UUID.getIntegerBits(t,32,47);
var thv = UUID.getIntegerBits(t,48,59) + '1'; // version 1, security version is 2
var csar = UUID.getIntegerBits(UUID.rand(4095),0,7);
var csl = UUID.getIntegerBits(UUID.rand(4095),0,7);
// since detection of anything about the machine/browser is far to buggy,
// include some more random numbers here
// if NIC or an IP can be obtained reliably, that should be put in
// here instead.
var n = UUID.getIntegerBits(UUID.rand(8191),0,7) +
UUID.getIntegerBits(UUID.rand(8191),8,15) +
UUID.getIntegerBits(UUID.rand(8191),0,7) +
UUID.getIntegerBits(UUID.rand(8191),8,15) +
UUID.getIntegerBits(UUID.rand(8191),0,15); // this last number is two octets long
return tl + tm + thv + csar + csl + n;
;

//Pull out only certain bits from a very large integer, used to get the time
//code information for the first part of a UUID. Will return zero's if there
//aren't enough bits to shift where it needs to.
UUID.getIntegerBits = function(val,start,end)
var base16 = UUID.returnBase(val,16);
var quadArray = new Array();
var quadString = '';
var i = 0;
for(i=0;i<base16.length;i++)
quadArray.push(base16.substring(i,i+1));

for(i=Math.floor(start/4);i<=Math.floor(end/4);i++)
if(!quadArray[i] || quadArray[i] == '') quadString += '0';
else quadString += quadArray[i];

return quadString;
;

//Replaced from the original function to leverage the built in methods in
//JavaScript. Thanks to Robert Kieffer for pointing this one out
UUID.returnBase = function(number, base)
return (number).toString(base).toUpperCase();
;

//pick a random number within a range of numbers
//int b rand(int a); where 0 <= b <= a
UUID.rand = function(max)
return Math.floor(Math.random() * (max + 1));
;

注: 使用时, 调用UUID.prototype.createUUID ()方法，返回32位UUID

参考技术A js 面向对象的写法，重写了valueOf方法和toString方法
然后给UUID原型添加方法
你也看到了UUID是自己定义的一个方法、在这里说就是一个对象吧 参考技术B 你可以理解为，给类添加一个方法。追问

UUID是一个类？prototype是一个固定写法？createUUID是一个方法？调用的时候用UUID.prototype.createUUID ()？UUID.prototype.createUUID ()为啥不写成function createUUID()方法，这种写法有什么好处？不太明白，您能帮我解释一下吗？

参考技术C javascript的神奇之处就是函数也是对象，prototype是对象原型，是想对象添加属性方法的接口本回答被提问者采纳