Function introduction and usage examples of prototype keyword in JS_javascript skills

The prototype keyword can add methods or properties to original JS objects or classes created by yourself.
Inheritance can also be implemented.
Example:

Copy code The code is as follows:

<script> <br><!-- In the original object in demo1 JS Add method --> <br>Number.prototype.add = function (num){ <br>return this num; <br>} <br>function but1_click(){ <br>alert((3).add( 8)); <br>} <br><!-- In the new object in demo2 JS, add attributes and methods--> <br>function Car(cColor,cWeight){ <br>this.cColor = cColor ; <br>this.cWeight = cWeight; <br>} <br>Car.prototype.drivers = new Array('zhangsan','lisi'); <br>Car.prototype.work = function (cLong){ <br>alert("I ran" cLong "km"); <br>} <br>function but2_click(){ <br>var c = new Car("red","5"); <br>c. drivers.push('zhaoliu'); <br>alert(c.drivers); <br>c.work(1); <br>} <br><!-- In the new object in demo3 JS, add attributes , the method is compactly written--> <br>function Rectangle(rWeight,rHeight){ <br>this.rWeight = rWeight; <br>this.rHeight = rHeight; <br>if( typeof this._init == ' undefined'){ <br>Rectangle.prototype.test = function (){ <br>alert("test"); <br>} <br>} <br>this._init = true; <br>} <br>function but3_click(){ <br>var t = new Rectangle(6,8); <br>t.test(); <br>} <br><!-- demo4 prototype inheritance--> <br>function objectA(){ <br>this.methodA = function (){ <br>alert("I am method A"); <br>} <br>} <br>function objectB(){ <br>this .methodB = function (){ <br>alert("I am method B"); <br>} <br>} <br>objectB.prototype = new objectA(); <br>function but4_click(){ <br>var t = new objectB(); <br>t.methodB(); <br>t.methodA(); <br>} <br></script>

< ;h2> Use of prototype keyword

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