function operationNumber(arg1,arg2,operator) {
var oper=['+','-','*','/'];
// 不合法的运算
if (isNaN(arg1)||isNaN(arg2)||oper.indexOf(operator)<0) {
return NaN;
}
// 除以0
if (operator==='/'&&Number(arg2)===0) {
return Infinity;
}
// 和0相乘
if (operator==='*'&&Number(arg2)===0) {
return 0;
}
// 相等两个数字相减
if ((arg1===arg2||Number(arg1)===Number(arg2))&&operator==='-') {
return 0;
}
var r1, r2, max,_r1,_r2;
try { r1 = arg1.toString().split(".")[1].length } catch (e) { r1 = 0 }
try { r2 = arg2.toString().split(".")[1].length } catch (e) { r2 = 0 }
max = Math.max(r1, r2)
_r1 = max-r1;
_r2 = max-r2;
if (_r1!==0) {
arg1=arg1+'0'.repeat(_r1)
}
if (_r2!==0) {
arg2=arg2+'0'.repeat(_r2)
}
arg1 = Number(arg1.toString().replace('.',''))
arg2 = Number(arg2.toString().replace('.',''))
var r3 = operator==='*'?(max*2):(operator==='/'?0:max);
var newNum = eval(arg1+operator+arg2);
if (r3!==0) {
var nStr = newNum.toString();
nStr = nStr.replace(/^-/,'');
if (nStr.length<r3+1) {
nStr = '0'.repeat(r3+1-nStr.length)+nStr;
}
nStr = nStr.replace(new RegExp('(\\\d{'+r3+'})$'),'.$1');
if (newNum<0) {
nStr = '-'+nStr;
}
newNum = nStr*1;
}
return newNum;
}将计算方法绑定在原型上
//加法
Number.prototype.myAdd = function(arg2) {
return operationNumber(this,arg2,'+');
}
//减法
Number.prototype.mySub = function(arg2) {
return operationNumber(this,arg2,'-');
}
//乘法
Number.prototype.myMul = function(arg2) {
return operationNumber(this,arg2,'*');
}
// 除法
Number.prototype.myDiv = function(arg2) {
return operationNumber(this,arg2,'/');
}
