5 ways to write JS object-oriented_js object-oriented

Java code

Copy code The code is as follows:

//First way of writing
function Circle(r) {
this.r = r;
}
Circle.PI = 3.14159;
Circle.prototype.area = function() {
return Circle.PI * this. r * this.r;
}
var c = new Circle(1.0);
alert(c.area());

Java code

Copy code The code is as follows:

//The second way of writing
var Circle = function() {
var obj = new Object();
obj.PI = 3.14159;
obj.area = function( r ) {
return this.PI * r * r;
}
return obj;
}
var c = new Circle();
alert( c.area( 1.0 ) );

Java code

Copy code The code is as follows:

//The third way of writing
var Circle = new Object();
Circle.PI = 3.14159;
Circle.Area = function( r ) {
return this.PI * r * r;
}
alert( Circle.Area( 1.0 ) );

Java code

Copy code The code is as follows:

//No. 4 A way to write
var Circle={
"PI":3.14159,
"area":function(r){
return this.PI * r * r;
}
} ;
alert( Circle.area(1.0) );

Java code

Copy code The code is as follows:

//The fifth way to write
var Circle = new Function("this.PI = 3.14159;this.area = function( r ) {return r*r*this .PI;}");
alert( (new Circle()).area(1.0) );

Let’s discuss these five writing methods, their advantages and disadvantages, and which one compares Norms, especially the last two, are often seen.