Question

84

javascript how to tell if one number is a multiple of another

rated 0 times [ 87] [ 3] / answers: 1 / hits: 103647 / 13 Years ago, fri, august 12, 2011, 12:00:00

I'm building a fairly calculation-heavy cart for a fabric store and have found myself needing to do a calculation on user inputted length * the baseprice per metre, but then checking the result to see if it is a multiple of the pattern length. If it is not a multiple, I need to find the closest multiple of the pattern length and change the result to that.

I need to also be able to do exactly the same calculation in PHP, but if anyone can help me out with the maths I can port anything that needs to be translated myself.

I am using jQuery 1.6.2 and already have the first part of the calculation done, I just need to check the result of (metres*price) against the pattern length.

Any help greatly appreciated

EDIT: These calculations all involve 2 decimal places for both the price and the pattern length. User inputted length may also contain decimals.

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

aubriea

Add To Favorites

Follow

Total Points: 641

Total Questions: 118

Total Answers: 101

Location: French Southern and Antarctic Lands

Member since Fri, Jan 6, 2023

1 Year ago

answered 13 Years ago ignacio · Accepted Answer

Use the % (modulus) operator in Javascript and PHP, which returns the remainder when a is divided by b in a % b. The remainder will be zero when a is a multiple of b.

Ex.

//Javascript

var result = userLength * basePrice;     //Get result

if(result % patternLength){              //Check if there is a remainder

  var remainder = result % patternLength; //Get remainder

  if(remainder >= patternLength / 2)      //If the remainder is larger than half of patternLength, then go up to the next mulitple

    result += patternLength - remainder;

  else                                    //Else - subtract the remainder to go down

    result -= remainder;

}

result = Math.round(result * 100) / 100;  //Round to 2 decimal places