TS regression: Narrowing of MathNodes by type · josdejong/mathjs

(23 条评论) (0 个反应) (0 位负责人)JavaScript (1,314 个派生)batch import

bughelp wantedtypescript

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描述

Describe the bug Prior to v11.3 (not sure how far back, but certainly at least 10), MathNode would be narrowed based on its type property:

const doStuffWithMathNode(node: MathNode) => {
  if (node.type === 'FunctionAssignmentNode) {
    // now TS knows that node is a FunctionAssignmentNode and lets you access associated props
    // like node.params
  }
  // back to being a wider MathNode
}

To Reproduce

working in v11.2 https://codesandbox.io/s/typescript-playground-export-forked-wnelgb?file=/index.ts
erroring in v11.3 https://codesandbox.io/s/typescript-playground-export-forked-ke8srr?file=/index.ts

贡献者指南

研究方向: 通过检查 mathjs 源代码中 MathNode 的类型定义来调查回归问题，特别是 v11.2 和 v11.3 之间的任何变化。使用提供的 codesandbox 示例来理解失败场景。查找最近修改类型收窄或 MathNode 类型的提交。审查项目的类型定义文件（例如 src/type/），并使用条件类型测试正确的类型收窄。
技术栈: typescript
领域: tooling
议题类型: 缺陷
难度: 2
预计时间: 1-3 小时
活动状态: 活跃
清晰度: 清晰
前置要求: TypeScript
新手友好度: 70