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js规则链实现

2026-03-16 08:28:46JavaScript

实现 JavaScript 规则链的方法

基于责任链模式的设计

责任链模式允许将多个处理对象串联成链，请求在链上传递直至被处理。以下是实现步骤：

js规则链实现

class Rule {
  constructor(condition, action) {
    this.condition = condition;
    this.action = action;
    this.nextRule = null;
  }

  setNextRule(rule) {
    this.nextRule = rule;
    return rule;
  }

  execute(context) {
    if (this.condition(context)) {
      this.action(context);
    }
    if (this.nextRule) {
      this.nextRule.execute(context);
    }
  }
}

// 使用示例
const rule1 = new Rule(
  (ctx) => ctx.value > 10,
  (ctx) => { ctx.result = '大于10' }
);

const rule2 = new Rule(
  (ctx) => ctx.value <= 10,
  (ctx) => { ctx.result = '小于等于10' }
);

rule1.setNextRule(rule2);
rule1.execute({ value: 5 }); // 输出: { value: 5, result: "小于等于10" }

使用数组实现的轻量级规则链

对于简单场景，可以用数组存储规则并按顺序执行：

js规则链实现

const ruleChain = [
  {
    condition: (ctx) => ctx.user.role === 'admin',
    action: (ctx) => { ctx.access = 'full' }
  },
  {
    condition: (ctx) => ctx.user.role === 'user',
    action: (ctx) => { ctx.access = 'partial' }
  }
];

function executeRules(context) {
  for (const rule of ruleChain) {
    if (rule.condition(context)) {
      rule.action(context);
      break; // 匹配后终止
    }
  }
}

支持异步处理的规则链

使用Promise实现异步规则链：

class AsyncRuleChain {
  constructor() {
    this.rules = [];
  }

  addRule(condition, action) {
    this.rules.push({ condition, action });
  }

  async execute(context) {
    for (const { condition, action } of this.rules) {
      if (await condition(context)) {
        await action(context);
        break;
      }
    }
  }
}

规则引擎库集成

现有库如json-rules-engine提供更完整的解决方案：

const { Engine } = require('json-rules-engine');

const engine = new Engine();
engine.addRule({
  conditions: {
    all: [{
      fact: 'temperature',
      operator: 'greaterThan',
      value: 60
    }]
  },
  event: {
    type: 'alert',
    params: {
      message: '温度过高!'
    }
  }
});

engine.run({ temperature: 70 }).then(events => {
  events.map(event => console.log(event.params.message));
});