常用加减乘除等方法汇总
直接上代码，逻辑简单，代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Math Methods</title>
</head>
<body>
<div id="div">加减乘除位移方法汇总</div>
<script type="application/javascript">
/**
* 向右移动小数点 ,相当于乘10的_pointcount次幂
* @param _number 操作的数字
* @param _pointcount 向右移动的位数
* @returns 移动以后的数字(number类型)
*/
var moveRight = function (_number, _pointcount) {
if (Number(_number) !== Number(_number)) {
return _number;
}
var flag = 1;
if (_number < 0) {
flag = -1;
_number = _number * -1;
}
var numStr = _number.toString();
var strArr = numStr.split(".");
var rightStr = strArr.length > 1 ? strArr[1] : "";
//在不足移动的位数后补0;
if (rightStr.length < _pointcount) {
var addZero = [];
for (var i = rightStr.length; i < _pointcount; i++) {
addZero.push("0");
}
rightStr = rightStr + addZero.join("");
}
return Number(strArr[0] + rightStr.substring(0, _pointcount) + "." + rightStr.substr(_pointcount)) * flag;
};
/**
* 向左移动小数点,相当于_number除以10的_pointcount次幂
* @param _number 操作的数字
* @param _pointcount 向左移动的位数
* @returns 移动以后的数字(number类型)
*/
var moveLeft = function (_number, _pointcount) {
//判断是否为数字,非数字直接返回本身
if (Number(_number) !== Number(_number)) {
return _number;
}
var flag = 1;
if (_number < 0) {
flag = -1;
_number = _number * -1;
}
//number转换为string ,方便后续操作。
var numStr = _number.toString();
//按照小数点分隔字符串,
var strArr = numStr.split(".");
var num = 0, zeroArr = [];
//生成移动位数+1的0 ,补到分隔后的第一个字符串中,兼容0.XXX的情况。开头多余的零会在调用Number方法时去掉。
while (num < _pointcount + 1) {
zeroArr.push("0");
num++;
}
var leftStr = zeroArr.join("") + strArr[0];
var leftArr = leftStr.split("")
//插入移动后的小数点。
leftArr.splice((leftStr.length - _pointcount), 0, '.');
var result = leftArr.join("");
//拼接原始值小数点后的数字
if (strArr.length > 1) {
result += strArr[1];
}
return Number(result) * flag;
};
/**
* 加法
* @param _num1
* @param _num2
* @param precision 精度
* @returns {*}
*/
var add = function (_num1, _num2, precision) {
if (!precision) {
precision = 2;
}
return moveLeft(moveRight(_num1, precision) + moveRight(_num2, precision), precision)
};
/**
* 减法
* @param minuend
* @param reduction
* @returns {*}
*/
var reduce = function (minuend, reduction, precision) {
if (!precision) {
precision = 2;
}
return moveLeft(moveRight(minuend, precision) - moveRight(reduction, precision), precision)
};
/**
* 乘法
* @param _num1
* @param _num2
* @returns {number}
*/
var multiplication = function (_num1, _num2, precision) {
if (!precision) {
precision = 2;
}
return moveLeft(moveRight(_num1, precision) * moveRight(_num2, precision), precision * 2)
};
/**
* 除法
* @param _num1 被除数
* @param _num2 除数
* @param precision 精度 整形,几位小数
* @returns {number}
*/
var division = function (_num1, _num2, precision) {
if (!precision) {
precision = 2;
}
return moveRight(_num1, precision) / moveRight(_num2, precision);
};
console.log(moveRight(0.9999999,3));
console.log(moveLeft(88888888888,2));
console.log(add(1.01,7.079,8));
console.log(reduce(8.01,1,2));
console.log(multiplication(1,8.88,2));
console.log(division(16,2,2))
</script>
</body>
</html>
