136 lines
4.1 KiB
JavaScript
136 lines
4.1 KiB
JavaScript
/**
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* https://github.com/nefe/number-precision
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*/
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'use strict';
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Object.defineProperty(exports, '__esModule', { value: true });
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/**
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* @desc 解决浮动运算问题，避免小数点后产生多位数和计算精度损失。
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* 问题示例：2.3 + 2.4 = 4.699999999999999，1.0 - 0.9 = 0.09999999999999998
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*/
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/**
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* 把错误的数据转正
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* strip(0.09999999999999998)=0.1
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*/
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function strip(num, precision) {
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if (precision === void 0) { precision = 12; }
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return +parseFloat(num.toPrecision(precision));
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}
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/**
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* Return digits length of a number
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* @param {*number} num Input number
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*/
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function digitLength(num) {
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// Get digit length of e
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var eSplit = num.toString().split(/[eE]/);
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var len = (eSplit[0].split('.')[1] || '').length - (+(eSplit[1] || 0));
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return len > 0 ? len : 0;
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}
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/**
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* 把小数转成整数，支持科学计数法。如果是小数则放大成整数
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* @param {*number} num 输入数
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*/
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function float2Fixed(num) {
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if (num.toString().indexOf('e') === -1) {
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return Number(num.toString().replace('.', ''));
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}
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var dLen = digitLength(num);
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return dLen > 0 ? strip(num * Math.pow(10, dLen)) : num;
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}
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/**
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* 检测数字是否越界，如果越界给出提示
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* @param {*number} num 输入数
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*/
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function checkBoundary(num) {
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if (_boundaryCheckingState) {
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if (num > Number.MAX_SAFE_INTEGER || num < Number.MIN_SAFE_INTEGER) {
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console.warn(num + " is beyond boundary when transfer to integer, the results may not be accurate");
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}
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}
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}
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/**
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* 精确乘法
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*/
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function times(num1, num2) {
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var others = [];
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for (var _i = 2; _i < arguments.length; _i++) {
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others[_i - 2] = arguments[_i];
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}
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if (others.length > 0) {
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return times.apply(void 0, [times(num1, num2), others[0]].concat(others.slice(1)));
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}
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var num1Changed = float2Fixed(num1);
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var num2Changed = float2Fixed(num2);
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var baseNum = digitLength(num1) + digitLength(num2);
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var leftValue = num1Changed * num2Changed;
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checkBoundary(leftValue);
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return leftValue / Math.pow(10, baseNum);
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}
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/**
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* 精确加法
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*/
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function plus(num1, num2) {
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var others = [];
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for (var _i = 2; _i < arguments.length; _i++) {
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others[_i - 2] = arguments[_i];
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}
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if (others.length > 0) {
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return plus.apply(void 0, [plus(num1, num2), others[0]].concat(others.slice(1)));
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}
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var baseNum = Math.pow(10, Math.max(digitLength(num1), digitLength(num2)));
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return (times(num1, baseNum) + times(num2, baseNum)) / baseNum;
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}
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/**
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* 精确减法
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*/
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function minus(num1, num2) {
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var others = [];
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for (var _i = 2; _i < arguments.length; _i++) {
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others[_i - 2] = arguments[_i];
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}
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if (others.length > 0) {
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return minus.apply(void 0, [minus(num1, num2), others[0]].concat(others.slice(1)));
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}
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var baseNum = Math.pow(10, Math.max(digitLength(num1), digitLength(num2)));
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return (times(num1, baseNum) - times(num2, baseNum)) / baseNum;
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}
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/**
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* 精确除法
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*/
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function divide(num1, num2) {
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var others = [];
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for (var _i = 2; _i < arguments.length; _i++) {
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others[_i - 2] = arguments[_i];
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}
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if (others.length > 0) {
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return divide.apply(void 0, [divide(num1, num2), others[0]].concat(others.slice(1)));
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}
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var num1Changed = float2Fixed(num1);
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var num2Changed = float2Fixed(num2);
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checkBoundary(num1Changed);
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checkBoundary(num2Changed);
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return times((num1Changed / num2Changed), Math.pow(10, digitLength(num2) - digitLength(num1)));
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}
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/**
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* 四舍五入
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*/
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function round(num, ratio) {
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var base = Math.pow(10, ratio);
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return divide(Math.round(times(num, base)), base);
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}
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var _boundaryCheckingState = true;
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/**
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* 是否进行边界检查，默认开启
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* @param flag 标记开关，true 为开启，false 为关闭，默认为 true
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*/
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function enableBoundaryChecking(flag) {
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if (flag === void 0) { flag = true; }
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_boundaryCheckingState = flag;
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}
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var index = { strip: strip, plus: plus, minus: minus, times: times, divide: divide, round: round, digitLength: digitLength, float2Fixed: float2Fixed, enableBoundaryChecking: enableBoundaryChecking };
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export default index;
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