Links
pseudo-selector a:link
a:visited
a:hover
text-decoration:none;
a:nth-child(n) # a refers type to be selected, not the parent node
var nn = new Object() # declare a new object and send it to nn
always declare a object before use it(like sending values to it)
function is object in js, like function Person(p1,p2){this.v1=p1;…} var n1 = new Person(,)
when in a new constructor, whatever variable or function should be after this. symbol to make it callable by the object.