angular - tslint no-var-keyword - "forbidden ' var' 关键字的目的是什么？

Question

tslint no-var-keyword(“禁止的‘var’关键字”)的目的是什么？ tslint 似乎在我的代码中每次出现 var 关键字时都会记录一个错误。 tslint 是否说明应在 ng2 中无条件排除 var 关键字？如果是，那为什么？

Answer 1

该规则及其基本原理记录在此处 https://palantir.github.io/tslint/rules/no-var-keyword/

Declaring variables using var has several edge case behaviors that make var unsuitable for modern code. Variables declared by var have their parent function block as their scope, ignoring other control flow statements. vars have declaration “hoisting” (similar to functions) and can appear to be used before declaration.

Variables declared by const and let instead have as their scope the block in which they are defined, and are not allowed to used before declaration or be re-declared with another const or let.

针对您的第二个问题，这与 Angular、ng2 或任何其他版本无关。这是一个 typescript 问题。是的，他们正试图让你放弃 var总之，赞成 let和 const .
let 和 var 的区别在于作用域。您必须在使用前进行声明，并且可以在嵌套范围内重新声明。在 TS 中，您也可以借此机会声明不同的类型，尽管我不认为这是一种编程风格。