check whether the number is nearly equal javascript

Question

I want to know whether it is possible?

Let Suppose:

var a = 2592;
var b = 2584;
if(a nearly equal to b) {
// do something
}

Answer 1

Like so.

var diff = Math.abs( a - b );

if( diff > 50 ) {
    console.log('diff greater than 50');
}

That would compare if the absolute difference is greater than 50 using Math.abs and simple comparison.

Answer 2

Here's the old school way to do it...

approxeq = function(v1, v2, epsilon) {
  if (epsilon == null) {
    epsilon = 0.001;
  }
  return Math.abs(v1 - v2) < epsilon;
};

so,

approxeq(5,5.000001)

is true, while

approxeq(5,5.1)

is false.

You can adjust pass in epsilons explicitly to suit your needs. One part in a thousand usually covers my javascript roundoff issues.