Number in JavaScript erroneous floating point numerical value

A bug JavaScript floating-point operations.
　　For example: 7 * 0.8 JavaScript is calculated: 5.6000000000000005

// Call: numberExcept (arg1, arg2)

// Return Value: arg1 arg2 exact result of dividing
function    numberExcept (arg1, arg2) {

  var t1=0,t2=0,r1,r2;
  try{t1=arg1.toString().split(".")[1].length}catch(e){}
  try{t2=arg2.toString().split(".")[1].length}catch(e){}
  with(Math){
  r1=Number(arg1.toString().replace(".",""))
  r2=Number(arg2.toString().replace(".",""))
  return (r1/r2)*pow(10,t2-t1);
  }
}

 

//transfer:

numberRide (arg1,arg2)

// Return Value: accurate results arg1 arg2 multiplying the
function numberRide (arg1, arg2)

{
  var m=0,s1=arg1.toString(),s2=arg2.toString();
  try{m+=s1.split(".")[1].length}catch(e){}
  try{m+=s2.split(".")[1].length}catch(e){}
  return Number(s1.replace(".",""))*Number(s2.replace(".",""))/Math.pow(10,m)
}

// Call: accAdd (arg1, arg2)
// Return Value: arg1 arg2 accurate results of adding
function accAdd (arg1, arg2) {
  var R1, R2, m;
  . Arg1.toString the try {R1 = () Split ( " . ") [. 1]} .length the catch (E) R1 = {0}
  the try {arg2.toString R2 = (). Split (". ") [. 1]} .length the catch (E) R2 = {0}
  m Math.pow = (10, Math.max (R1, R2))
  return (arg1 arg2 * * m + m) / m
}

Subtraction function

function accSub(arg1, arg2) {
var r1, r2, m, n;
try { r1 = arg1.toString().split(".")[1].length } catch (e) { r1 = 0 }
try { r2 = arg2.toString().split(".")[1].length } catch (e) { r2 = 0 }
m = Math.pow(10, Math.max(r1, r2));
//last modify by deeka
//动态控制精度长度
n = (r1 >= r2) ? r1 : r2;
return ((arg1 * m - arg2 * m) / m).toFixed(n);
}