js 加減乘除bug修正
原理都是先轉(zhuǎn)換為整數(shù)
=====
經(jīng)過測試的正確方法

// 加
export function floatAdd(a, b) {
  let c, d, e
  try {
    c = a.toString().split('.')[1].length
  } catch (f) {
    c = 0
  }
  try {
    d = b.toString().split('.')[1].length
  } catch (f) {
    d = 0
  }
  // eslint-disable-next-line no-return-assign,no-sequences
  return e = Math.pow(10, Math.max(c, d)), (floatMul(a, e) + floatMul(b, e)) / e
}

// 減
export function floatSub(a, b) {
  let c, d, e
  try {
    c = a.toString().split('.')[1].length
  } catch (f) {
    c = 0
  }
  try {
    d = b.toString().split('.')[1].length
  } catch (f) {
    d = 0
  }
  // eslint-disable-next-line no-return-assign,no-sequences
  return e = Math.pow(10, Math.max(c, d)), (floatMul(a, e) - floatMul(b, e)) / e
}

// 乘
export function floatMul(a, b) {
  var c = 0
  var d = a.toString()
  var e = b.toString()
  try {
    c += d.split('.')[1].length
    // eslint-disable-next-line no-empty
  } catch (f) {}
  try {
    c += e.split('.')[1].length
    // eslint-disable-next-line no-empty
  } catch (f) {}
  return Number(d.replace('.', '')) * Number(e.replace('.', '')) / Math.pow(10, c)
}

// 除
export function floatDiv(a, b) {
  let c; let d; let e = 0
  var f = 0
  try {
    e = a.toString().split('.')[1].length
    // eslint-disable-next-line no-empty
  } catch (g) {}
  try {
    f = b.toString().split('.')[1].length
    // eslint-disable-next-line no-empty
  } catch (g) {}
  // eslint-disable-next-line no-return-assign,no-sequences
  return c = Number(a.toString().replace('.', '')), d = Number(b.toString().replace('.', '')), floatMul(c / d, Math.pow(10, f - e))
}

方法1

//加 
function floatAdd(arg1,arg2){ 
  var r1,r2,m; 
  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)); 
  return (arg1*m+arg2*m)/m; 
} 
   
//減 
function floatSub(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)); 
 //動態(tài)控制精度長度 
 n=(r1>=r2)?r1:r2; 
 return ((arg1*m-arg2*m)/m).toFixed(n); 
} 
   
//乘 
function floatMul(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); 
} 
   
   
//除 
function floatDiv(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){} 
    
  r1=Number(arg1.toString().replace(".","")); 
  
  r2=Number(arg2.toString().replace(".","")); 
  return (r1/r2)*Math.pow(10,t2-t1); 
}

方法二

/** 
 ** 除法函數(shù)，用來得到精確的除法結(jié)果
 ** 說明：javascript的除法結(jié)果會有誤差，在兩個浮點數(shù)相除的時候會比較明顯。這個函數(shù)返回較為精確的除法結(jié)果。
 ** 調(diào)用：accDiv(arg1,arg2)
 ** 返回值：arg1除以arg2的精確結(jié)果
 **/
function accDiv(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);
    }
}

/**
 ** 乘法函數(shù)，用來得到精確的乘法結(jié)果
 ** 說明：javascript的乘法結(jié)果會有誤差，在兩個浮點數(shù)相乘的時候會比較明顯。這個函數(shù)返回較為精確的乘法結(jié)果。
 ** 調(diào)用：accMul(arg1,arg2)
 ** 返回值：arg1乘以 arg2的精確結(jié)果
 **/
function accMul(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);
}

/**
 ** 減法函數(shù)，用來得到精確的減法結(jié)果
 ** 說明：javascript的減法結(jié)果會有誤差，在兩個浮點數(shù)相減的時候會比較明顯。這個函數(shù)返回較為精確的減法結(jié)果。
 ** 調(diào)用：accSub(arg1,arg2)
 ** 返回值：arg1加上arg2的精確結(jié)果
 **/
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 //動態(tài)控制精度長度
    n = (r1 >= r2) ? r1 : r2;
    return ((arg1 * m - arg2 * m) / m).toFixed(n);
}

function accAdd(arg1, arg2) {
    var r1, r2, m, c;
    try {
        r1 = arg1.toString().split(".")[1].length;
    }
    catch (e) {
        r1 = 0;
    }
    try {
        r2 = arg2.toString().split(".")[1].length;
    }
    catch (e) {
        r2 = 0;
    }
    c = Math.abs(r1 - r2);
    m = Math.pow(10, Math.max(r1, r2));
    if (c > 0) {
        var cm = Math.pow(10, c);
        if (r1 > r2) {
            arg1 = Number(arg1.toString().replace(".", ""));
            arg2 = Number(arg2.toString().replace(".", "")) * cm;
        } else {
            arg1 = Number(arg1.toString().replace(".", "")) * cm;
            arg2 = Number(arg2.toString().replace(".", ""));
        }
    } else {
        arg1 = Number(arg1.toString().replace(".", ""));
        arg2 = Number(arg2.toString().replace(".", ""));
    }
    return (arg1 + arg2) / m;
}

出自 https://www.cnblogs.com/coprince/p/5282532.html