Js - 使用运算符作为字符串评估数学表达式的替代方法

Question

我有一个库，它具有根据某些字段过滤对象的功能（每个字段都有特定类型 - 更多信息请参见 https://github.com/jy95/mediaScan/wiki）

最大的问题是处理来自多个来源的数字属性

// to handle number operations
export interface NumberExpressionObject {
    operator: "==" | ">" | "<" | ">=" | "<=";
    number: number;
}

// additional Properties
export interface AdditionalProperties {
    type: AdditionalPropertiesType;
    name: string;
    value: boolean | string | string[] | number | NumberSearchSyntax;
}

例如：

expect((libInstance.filterTvSeries({
            additionalProperties: [
                {type: "number", name: "whateverFieldThatDoesn'tExist", value: "<50"},
                {type: "number", name: "AnotherField", value: undefined},
                {type: "number", name: "AnotherField2", value: "<=25"},
                {type: "number", name: "AnotherField3", value: ">25"},
                {type: "number", name: "AnotherField4", value: "==25"},
            ],
            season: ">=4",
        }))).toEqual(
            new Map(),
        );

每一个必须首先对应以下正则表达式：

const validExpression = /^(==|>|<|>=|<=)(\d+)$/;

然后将被这个函数求值:

function resolveExpression(property: string,
                           expressionObject: MediaScanTypes.NumberExpressionObject,
                           object: MediaScanTypes.TPN | MediaScanTypes.TPN_Extended): boolean {
    return eval(`${object[property]}${expressionObject.operator}${expressionObject.number}`);
}

我想知道有什么更简洁的方法来做到这一点...请避免像 switch case 这样简单的答案：我测试了它，但在我的测试中它仍然比 eval 慢...

函数构造函数对我来说和 eval 一样..

我读过的以前的帖子：
Evaluating a string as a mathematical expression in JavaScript
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function
...

Answer 1

为运算符实现函数

操作数 = { '>': (a, b) => a > b, '>=': (a, b) => a >= b };

ops[expressionObject.operator](对象[属性],expressionObject.number)
如果表达式始终按预期有效。那么下面应该更快，因为没有解析。

eval(${object[property]}${expression})

Answer 2

你可以有一些从 operator 到 function

的映射

const ops = {'==':(a,b)=> a == b};
return ops[${expressionObject.operator}](${object[property]},${expressionObject.number})

Js - 使用运算符作为字符串评估数学表达式的替代方法

Js - Alternatives to eval mathematical expression with operator as string

javascript

eval

node.js

typescript