Shulou(Shulou.com)06/02 Report--

This article mainly introduces how to find the round area of JavaScript, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

The method of JavaScript to calculate the circle area: 1, to calculate the circle area by the way of "function Area () {return (3.14*this.r*this.r)}"; 2, to calculate the circle area by "return r*r*Math.PI" and so on.

This article operating environment: Windows7 system, javascript1.8.5 version, DELL G3 computer

Summary of the area of finding a circle by JS function

JS function / / 1.function circle (r) {this.r=rthis.Area=Areathis.Circum=Circum} function Circum () {return (3.14*2*this.r)} function Area () {return (3.14*this.r*this.r)} r=parseInt (prompt ("Please enter radius:", "); / / parseInt () function parses a string and returns an integer var newcircle=new circle (r); var Circumcapital=newcircle.Circum (); var Areacapital=newcircle.Area () [xss_clean] ("perimeter:" + Circumcapital+ ";"); [xss_clean] ("area:" + Areacapital+ "); / / 2.var area_of_circle = new Function (" r "," return r*r*Math.PI "); / / create a function object var rCircle1 = 2stroke / radius of a given circle var area = area_of_circle (rCircle1); alert (" circle area with radius 2: "+ area); var rCircle2 = 3 / / the radius of the given circle var area = area_of_circle (rCircle2); alert ("the area of the circle with radius 3 is:" + area); / / 3.var r=prompt ("enter the radius of the circle", "Please enter the radius:"); / / prompt () method is used to display the dialog box if (ringing null) {undefined var square=r*r*Math.PI that prompts the user for input [xss_clean] ("the area of the circle is:" + square);} else {undefined alert ("incorrect input data");}

1. 、 2. And 3. There are three different ways to calculate the area of a circle. In the first method, the perimeter calculation method is added. In the second method, I define a common function for area_of_circle (area). No matter how much the radius is, we can call the area function, which saves the copying of the function of finding area. The third method pays attention to the prompt () function, and the third one has an if judgment to determine whether the input is invalid.

What is JavaScript JS is the abbreviation of JavaScript, it is a literal scripting language, its interpreter is called JavaScript engine, is a part of the browser, mainly used for web development, can add a variety of dynamic effects to the website, make the web page more beautiful.

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