js 计算乘算时数字溢出
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场景项目上为了计算税率相乘，金额有小数点乘以税率后会导致部分数字溢出，为了解决数字溢出。
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使用 bignumber.js 库：
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安装 npm run install bignumber.js
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使用：
- 效果图
// 引入BigNumberconst BigNumber = require("bignumber.js");created() {console.log("直接相乘有数字溢出问题115.75 * 0.06=" + 115.75 * 0.06);console.log("115.75 * 0.06=" + this.getCommonNum(115.75, 0.06));console.log("620.75 * 0.06=" + this.getCommonNum(620.75, 0.06));console.log("4455.45 * 0.01=" + this.getCommonNum(4455.45, 0.01));}/*** value 金额* ratio 税率* 金额税率计算如果是整数取整，小数点小于两位保留当前数字，小数点大于3为，取第三位如果大于5需要往前面一维进一，小于5保留小数点后两位即可*/getCommonNum(value, ratio) {// vue js计算乘算时数字溢出// 使用BigNumberconst largeNumber1 = new BigNumber(value);const largeNumber2 = new BigNumber(ratio);const result = largeNumber1.times(largeNumber2);const num = Number(result.toString());const numStr = result ? result.toString() : 0;// 判断是否是整数if (Number.isInteger(num)) {return num;} else {if (numStr.includes(".")) {const numLen = numStr.split(".")[1].length;if (numLen <= 2) {return num;} else if (numLen >= 3) {const first = numStr.split(".")[0];const second = numStr.split(".")[1];const twoNum = Number(second.slice(0, 2));const threeNum = Number(second.slice(2, 3));if (threeNum < 5) {const conversion = first + "." + twoNum;return Number(conversion);} else {const num1 = first + "." + twoNum;const num12 = Number(num1) + 0.01;return Number(num12);}} else {return num;}}}}
