JavaScript implements multiple method instances of classes_javascript skills

Construction method

Copy code The code is as follows:

function coder()
{
this.name = 'Modern Magic';
this.job = 'Web Developer';
this.coding = function ()
{ alert('I'm writing code'); }
}

var coder = new coder();
alert(coder.name);
coder.coding();

Factory method

Copy code The code is as follows:

function createCoderFactory()
{
var obj = new Object();
obj.name = 'Modern Magic';
obj.job = 'Programmer';
obj.coding = function ()
{
alert('I'm writing code');
};
return obj;
}
var coder = createCoderFactory();
alert(coder.name);
coder.coding();

Both factory methods and constructor methods have the same disadvantage, that is, every time an instance is created, each function of the class will be instantiated.

Prototype chain

Copy code The code is as follows:

function coder(){}
coder.prototype.name = 'Modern Magic';
coder.prototype.job = 'Programmer';
coder.prototype.coding = function(){
alert('I am writing code ');
};
var coder = new coder();
alert(coder.name);
coder.coding();

The prototype chain has One disadvantage is that all its properties are shared. As long as one instance changes, the others will change accordingly. Such as:

Copy code The code is as follows:

var coder1 = new coder();
var coder2 = new coder();
alert(coder1.name); /*Show modern magic*/
coder2.name = 'nowamagic';
alert(coder1.name); /*Show nowamagic* /
alert(coder2.name); /*This also shows nowamagic*/

Mixed method
The above three have their own shortcomings, so we need to improve them.

Copy code The code is as follows:

function coder()
{
this .name = 'Modern Magic';
this.job = 'Programmer';
}
coder.prototype.coding = function(){
alert('I'm writing code');
};

Dynamic original chain
There is another way to solve the first three shortcomings.

Copy code The code is as follows:

function coder()
{
this .name = 'Modern Magic';
this.job = 'Programmer';
if (typeof(coder._init) == 'undefined')
{
this.coding = function ( :)