The ultimate html resource About the Double-Underlined Links INTRODUCTION home | about | non-technical introduction newsletter archive | PRIMERS html| MySpace html| ad banners| perl & cgi| asp| javascript| database - sql| HTML & GRAPHICS TUTORIALS getting started| backgrounds| buttons| browser specific| colors| forms| frames| html 4.01 tags| html 4.01 ref| image maps| tables| web graphics| BEYOND HTML asp| cascading style sheets| css keyword ref| cgi scripting| dhtml/layers| dot net| java applets| javascript| javascript keyword ref| javascript script tips| php| security| SEO| vb script keyword ref| webmaster tips| webmaster projects| webmaster toolbox| video| xml| general reference pieces| the master list| NEED HELP? discussion boards| mentors| technology jobs| WEB DEVELOPMENT earthwebdeveloper.com| javascripts.com| Become a Partner internet.commerce HTML Goodies : Primers : Javascript Primers: The JavaScript Diaries: Part 14 Related Articles •The JavaScript Diaries: Part 13 •The JavaScript Diaries: Part 12 •The JavaScript Diaries: Part 11 •The JavaScript Diaries: Part 10 •The JavaScript Diaries: Part 9 •The JavaScript Diaries: Part 8 •The JavaScript Diaries: Part 7 •The JavaScript Diaries: Part 6 •The JavaScript Diaries: Part 5 •The JavaScript Diaries: Part 4 •The JavaScript Diaries: Part 3 •The JavaScript Diaries: Part 2 •The JavaScript Diaries: Part 1 Web Development Daily Newsletter Other Related Newsletters The JavaScript Diaries: Part 14 By Lee Underwood The Math object is a predefined JavaScript object used to perform mathematical operations. It's also used to obtain the values of predefined mathematical constants, i.e., Pi (π) or the square root of a number. In addition, it can also be used to generate random numbers. It's important to remember that the Math object begins with an uppercase "M." If a lower case "m" is used, the JavaScript interpreter will not recognize it as an object. (Note: We won't cover all of these properties and methods in detail as some of them are a little more complicated than what we are dealing with right now.) Properties Name Description E The value of Euler's constant, approximately 2.718 LN2 The natural logarithm of 2, approximately 0.693 LN10 The natural logarithm of 10, approximately 2.302 LOG2E The base 2 logarithm of E, approximately 1.442 LOG10E The base 10 logarithm of E, approximately 0.434 PI (π) The ratio of the circumference of a circle to its diameter, approximately 3.14159 SQRT1_2 Square root of 1/2; equivalently, 1 over the square root of 2, approximately 0.707 SQRT2 Square root of 2, approximately 1.414 Using Pi You can use this script to calculate the circumference of a circle using Pi by entering the radius: function circum() { var radius = prompt("Enter the radius of the circle",""); var circle = 2 * Math.PI * radius; alert("The circumference is "+circle) } Let's see what we did in this script. First, we created a function called circum. Then, we declared the variable radius and gave it the value of the results of a prompt box, which obtains the size of the radius from the user. Next, we declared the variable circle and gave it the formula which will calculate the actual circumference of the circle, based on the information given to the radius variable. Finally, an alert box displays the results of the calculation. You would then add this in the body section of the page in order to call the script above: <form> <input type="button" value="Calculate the circumference" onclick="circum()"> </form> Let's take a look at the JavaScript math methods and see what we can do with them. Go to page: 1  2  3  Next   Tools: Add htmlgoodies.com to your favorites Add htmlgoodies.com to your browser search box IE 7 | Firefox 2.0 | Firefox 1.5.x Receive news via our XML/RSS feed