如何在不使用模数的情况下在javascript中获得余数

Question

I'm having some issues with this code. The online applet I'm using is telling me that when it's expecting 1, it's actually getting -2 and it's saying I'm wrong. To me the code looks correct. Does anyone see something wrong here?

This is what I have so far:

function modulo(num1, num2) {
  if(isNaN(num1) || isNaN(num2)){
      return NaN;
  }
  if(num1 === 0){
      return 0;
  }
  if(num2 === 0){
      return NaN;
  }

  var quot = num1 - Math.floor(num1/num2)*num2;

  if(num1 < 0){
      return -(quot);
  }
  else{
      return quot;
  }
}

Answer 1

You need to use Math.abs at some point:

function modulo(num1, num2) {
     if(isNaN(num1) || isNaN(num2)){
                              return NaN;
                            }
     if(num1 === 0){
            return 0;
            }
     if(num2 === 0){
            return NaN;
     }


       var newNum1 = Math.abs(num1);
       var newNum2 = Math.abs(num2);

       var quot = newNum1 - Math.floor( newNum1 / newNum2 ) * newNum2 ;

       if(num1 < 0){
             return -(quot);
       }
       else{
             return quot;
       }
  }

Answer 2

Edit : Fixed some things

 function divide() { var number = Number(document.getElementById('number').value); var divide = Number(document.getElementById('divide').value); var number2 = Number(Math.floor(number/divide)); var remainder = Number(number - (number2 * divide)); var result = remainder; document.getElementById('quotient').innerHTML = "Quotient : " + number2; document.getElementById('result').innerHTML = "Remainder : " + result; } 

 <label>Number: </label><input type="number" id="number"> <label>Divisor: </label><input type="number" id="divide"> <div id="quotient">Quotient: </div> <div id="result">Remainder: </div> <button onclick="divide()">Divide</button> 

Answer 3

The issue was with your return statement. It should have been return quot - num2 when num1 is less than 0.

I made it work and passes the several tests in the JSBin: http://jsbin.com/rufumi/3/edit?js,console

Cheers

Answer 4

I think this code is compliant with ECMAScript's definition of the modulus operator .

function modulo(num1, num2) {
  num1 = +num1;
  num2 = +num2;
  if (!num2 || !Number.isFinite(num1)) return NaN;
  if (!num1 || !Number.isFinite(num2)) return num1;
  return num1 - Math.trunc(num1/num2)*num2;
}