JavascriptStudyMemo
Javascript basic concept.....
我们提供的服务有:网站制作、做网站、微信公众号开发、网站优化、网站认证、黄岛ssl等。为上1000+企事业单位解决了网站和推广的问题。提供周到的售前咨询和贴心的售后服务,是有科学管理、有技术的黄岛网站制作公司
[@more@]- Instance property: property defined in constructor:
function Circle(radius) { this.radius = radius; }
- Class property: property belongs to class. all instances share the only
copy of class property:
Circle.PI = 3.141592; Circle.UNIT = new Circle(1);
- Instance method:An instance method can be invoked for any instance of a
class, but this does not mean that each object contains its own private copy
of the method, as it does with instance properties.Instead, instance method
is defined by prototype property:
Circle.prototype.area() { // notes: must explicitly specify thiskeyword to property return Circle.PI * this.radius * this.radius; }
- Class method: method associated with a class rather than an instance of
a class:
Circle.max = function (a,b) { if (a.r > b.r) { return a; }else { return b; } }
Function execute & Call Object Concept
When Invoke a function, the function scope is set to scope chain, and then add a new object known as call object to the front of the scope chain. the call object is initialized with parameters, local variable. If a nested function is invoked, the scope chain includes three objects: its own call object, the call object of outer object , and the global object.
uniqueID = function(){ // user can set id back to 0 by: uniqueID.id = 0 if (!arguments.callee.id) arguments.callee.id = 0; return arguments.callee.id++; }; uid = (function(){ // closure, id is persistent and private var id = 0; return function(){ return id++; }; })(); var ret = ""; var i = 10; while (i--) { ret += uniqueID() + "t"; uniqueID.id = 0; } alert(ret); i = 10; ret = ""; while (i--) { ret += uid() + "t"; } alert(ret);
当前标题:JavascriptStudyMemo
浏览地址:http://ybzwz.com/article/ggsgdo.html